{"id":"CVE-2026-100662","aliases":["EUVD-2026-87756","GHSA-f64r-x647-cg8w","GHSA-w648-8654-gr82","UBUNTU-CVE-2026-100662"],"status":"published","title":"Netty HTTP/3 QPACK encoder-stream unbounded memory exhaustion DoS","description":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption vulnerability in the QPACK encoder-stream instruction decoder (QpackEncoderHandler, installed on the peer-initiated unidirectional QPACK encoder stream, type 0x02). The handler accepts an attacker-declared string-literal length of up to Integer.MAX_VALUE (~2 GiB) for the Name Length and Value Length fields of the \"Insert With Literal Name\" instruction (RFC 9204 §4.3.3), with no per-instruction or per-literal length cap and no cumulation-size limit; the existing HTTP/3 limits (maxHeaderListSize, maxUnknownFramePayloadLength, DEFAULT_MAX_FIELD_SECTION_SIZE) are not applied to this handler. A remote, unauthenticated peer with an established HTTP/3 connection to a default Netty HTTP/3 server can declare a very large literal length and then trickle fewer bytes than declared, causing the ByteToMessageDecoder MERGE cumulator to retain and grow the per-connection buffer, and ultimately triggering a large byte-array allocation. This leads to unbounded per-connection heap growth and OutOfMemoryError, resulting in denial of service. Fixed in 4.2.18.Final.","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":"2026-11-12","score":0.00416,"percentile":0.36367,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-400"],"published":"2026-09-26T13:23:28Z","modified":"2026-10-28T02:30:42Z","affected":[{"source":"osv","ecosystem":"Ubuntu:Pro:14.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:3.2.6.Final-2","1:3.2.6.Final-2+deb8u2build0.14.04.1~esm1","1:3.2.6.Final-2+deb8u2ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:16.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:3.2.6.Final-2","1:4.0.32-1","1:4.0.33-1","1:4.0.34-1","1:4.0.34-1ubuntu0.1~esm1","1:4.0.34-1ubuntu0.1~esm2","1:4.0.34-1ubuntu0.1~esm3","1:4.0.34-1ubuntu0.1~esm4","1:4.0.34-1ubuntu0.1~esm5"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.7-4","1:4.1.7-4ubuntu0.1~esm1","1:4.1.7-4ubuntu0.1","1:4.1.7-4ubuntu0.1+esm1","1:4.1.7-4ubuntu0.1+esm2","1:4.1.7-4ubuntu0.1+esm3","1:4.1.7-4ubuntu0.1+esm4","1:4.1.7-4ubuntu0.1+esm5","1:4.1.7-4ubuntu0.1+esm6","1:4.1.7-4ubuntu0.1+esm7"]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.33-1","1:4.1.33-2","1:4.1.33-3","1:4.1.45-1","1:4.1.45-1ubuntu0.1~esm1","1:4.1.45-1ubuntu0.1~esm2","1:4.1.45-1ubuntu0.1~esm3","1:4.1.45-1ubuntu0.1~esm4","1:4.1.45-1ubuntu0.1~esm6","1:4.1.45-1ubuntu0.1~esm7"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.48-4","1:4.1.48-4+deb11u1build0.22.04.1","1:4.1.48-4+deb11u2build0.22.04.1","1:4.1.48-4+deb11u2ubuntu0.1~esm1","1:4.1.48-4+deb11u2ubuntu0.1~esm2","1:4.1.48-4+deb11u2ubuntu0.1","1:4.1.48-4+deb11u2ubuntu0.1+esm1","1:4.1.48-4+deb11u2ubuntu0.1+esm3","1:4.1.48-4+deb11u2ubuntu0.2","1:4.1.48-4+deb11u2ubuntu0.2+esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.48-7","1:4.1.48-8","1:4.1.48-9","1:4.1.48-9ubuntu0.1~esm1","1:4.1.48-9ubuntu0.1~esm2","1:4.1.48-9ubuntu0.1","1:4.1.48-9ubuntu0.1+esm1","1:4.1.48-9ubuntu0.1+esm3","1:4.1.48-9ubuntu0.2","1:4.1.48-9ubuntu0.2+esm1","1:4.1.48-9ubuntu0.2+esm2"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.48-16","1:4.1.48-16ubuntu1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:26.04:LTS","package":"netty","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:4.1.48-10","1:4.1.48-11","1:4.1.48-12","1:4.1.48-13","1:4.1.48-14","1:4.1.48-16","1:4.1.48-16ubuntu0.1~esm2"]}],"products":[{"vendor":"netty","product":"netty"}],"references":[{"url":"https://github.com/netty/netty/security/advisories/GHSA-f64r-x647-cg8w","tags":["vendor-advisory","exploit","advisory","report"]},{"url":"https://www.vulncheck.com/advisories/netty-http-3-qpack-encoder-stream-unbounded-memory-exhaustion-dos","tags":["third-party-advisory","advisory","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100662","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-w648-8654-gr82"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/100xxx/CVE-2026-100662.json","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-100662","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100662","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-100662","title":"Netty HTTP/3 QPACK encoder-stream unbounded memory exhaustion DoS","description":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption vulnerability in the QPACK encoder-stream instruction decoder (QpackEncoderHandler, installed on the peer-initiated unidirectional QPACK encoder stream, type 0x02). The handler accepts an attacker-declared string-literal length of up to Integer.MAX_VALUE (~2 GiB) for the Name Length and Value Length fields of the \"Insert With Literal Name\" instruction (RFC 9204 §4.3.3), with no per-instruction or per-literal length cap and no cumulation-size limit; the existing HTTP/3 limits (maxHeaderListSize, maxUnknownFramePayloadLength, DEFAULT_MAX_FIELD_SECTION_SIZE) are not applied to this handler. A remote, unauthenticated peer with an established HTTP/3 connection to a default Netty HTTP/3 server can declare a very large literal length and then trickle fewer bytes than declared, causing the ByteToMessageDecoder MERGE cumulator to retain and grow the per-connection buffer, and ultimately triggering a large byte-array allocation. This leads to unbounded per-connection heap growth and OutOfMemoryError, resulting in denial of service. Fixed in 4.2.18.Final.","status":"published","published":"2026-09-26T13:23:28.99Z","modified":"2026-09-30T14:53:30.335Z","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-400"],"updated_at":"2026-11-02T14:20:06.925367Z"}],"euvd":[{"id":"EUVD-2026-87756","description":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption vulnerability in the QPACK encoder-stream instruction decoder (QpackEncoderHandler, installed on the peer-initiated unidirectional QPACK encoder stream, type 0x02). The handler accepts an attacker-declared string-literal length of up to Integer.MAX_VALUE (~2 GiB) for the Name Length and Value Length fields of the \"Insert With Literal Name\" instruction (RFC 9204 §4.3.3), with no per-instruction or per-literal length cap and no cumulation-size limit; the existing HTTP/3 limits (maxHeaderListSize, maxUnknownFramePayloadLength, DEFAULT_MAX_FIELD_SECTION_SIZE) are not applied to this handler. A remote, unauthenticated peer with an established HTTP/3 connection to a default Netty HTTP/3 server can declare a very large literal length and then trickle fewer bytes than declared, causing the ByteToMessageDecoder MERGE cumulator to retain and grow the per-connection buffer, and ultimately triggering a large byte-array allocation. This leads to unbounded per-connection heap growth and OutOfMemoryError, resulting in denial of service. Fixed in 4.2.18.Final.","status":"published","published":"2026-09-26T13:23:28Z","modified":"2026-09-30T14:53:30Z","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":"2026-11-02T17:27:49.499669Z"}],"ghsa":[{"id":"GHSA-w648-8654-gr82","title":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final...","description":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption vulnerability in the QPACK encoder-stream instruction decoder (QpackEncoderHandler, installed on the peer-initiated unidirectional QPACK encoder stream, type 0x02). The handler accepts an attacker-declared string-literal length of up to Integer.MAX_VALUE (~2 GiB) for the Name Length and Value Length fields of the \"Insert With Literal Name\" instruction (RFC 9204 §4.3.3), with no per-instruction or per-literal length cap and no cumulation-size limit; the existing HTTP/3 limits (maxHeaderListSize, maxUnknownFramePayloadLength, DEFAULT_MAX_FIELD_SECTION_SIZE) are not applied to this handler. A remote, unauthenticated peer with an established HTTP/3 connection to a default Netty HTTP/3 server can declare a very large literal length and then trickle fewer bytes than declared, causing the ByteToMessageDecoder MERGE cumulator to retain and grow the per-connection buffer, and ultimately triggering a large byte-array allocation. This leads to unbounded per-connection heap growth and OutOfMemoryError, resulting in denial of service. Fixed in 4.2.18.Final.","status":"published","published":"2026-09-26T15:31:18Z","modified":"2026-09-26T15:31:23Z","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-400"],"updated_at":"2026-11-02T15:12:30.047516Z"}],"nvd":[{"id":"CVE-2026-100662","description":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption vulnerability in the QPACK encoder-stream instruction decoder (QpackEncoderHandler, installed on the peer-initiated unidirectional QPACK encoder stream, type 0x02). The handler accepts an attacker-declared string-literal length of up to Integer.MAX_VALUE (~2 GiB) for the Name Length and Value Length fields of the \"Insert With Literal Name\" instruction (RFC 9204 §4.3.3), with no per-instruction or per-literal length cap and no cumulation-size limit; the existing HTTP/3 limits (maxHeaderListSize, maxUnknownFramePayloadLength, DEFAULT_MAX_FIELD_SECTION_SIZE) are not applied to this handler. A remote, unauthenticated peer with an established HTTP/3 connection to a default Netty HTTP/3 server can declare a very large literal length and then trickle fewer bytes than declared, causing the ByteToMessageDecoder MERGE cumulator to retain and grow the per-connection buffer, and ultimately triggering a large byte-array allocation. This leads to unbounded per-connection heap growth and OutOfMemoryError, resulting in denial of service. Fixed in 4.2.18.Final.","status":"published","published":"2026-09-26T14:16:49.257Z","modified":"2026-09-30T15:22:15.423Z","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-400"],"updated_at":"2026-11-02T14:12:52.081323Z"}],"osv":[{"id":"CVE-2026-100662","title":"Netty HTTP/3 QPACK encoder-stream unbounded memory exhaustion DoS","description":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption vulnerability in the QPACK encoder-stream instruction decoder (QpackEncoderHandler, installed on the peer-initiated unidirectional QPACK encoder stream, type 0x02). The handler accepts an attacker-declared string-literal length of up to Integer.MAX_VALUE (~2 GiB) for the Name Length and Value Length fields of the \"Insert With Literal Name\" instruction (RFC 9204 §4.3.3), with no per-instruction or per-literal length cap and no cumulation-size limit; the existing HTTP/3 limits (maxHeaderListSize, maxUnknownFramePayloadLength, DEFAULT_MAX_FIELD_SECTION_SIZE) are not applied to this handler. A remote, unauthenticated peer with an established HTTP/3 connection to a default Netty HTTP/3 server can declare a very large literal length and then trickle fewer bytes than declared, causing the ByteToMessageDecoder MERGE cumulator to retain and grow the per-connection buffer, and ultimately triggering a large byte-array allocation. This leads to unbounded per-connection heap growth and OutOfMemoryError, resulting in denial of service. Fixed in 4.2.18.Final.","status":"published","published":"2026-09-26T13:23:28.99Z","modified":"2026-10-28T02:30:42.349664399Z","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-400"],"updated_at":"2026-11-02T15:44:53.490346Z"},{"id":"UBUNTU-CVE-2026-100662","description":"Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption vulnerability in the QPACK encoder-stream instruction decoder (QpackEncoderHandler, installed on the peer-initiated unidirectional QPACK encoder stream, type 0x02). The handler accepts an attacker-declared string-literal length of up to Integer.MAX_VALUE (~2 GiB) for the Name Length and Value Length fields of the \"Insert With Literal Name\" instruction (RFC 9204 §4.3.3), with no per-instruction or per-literal length cap and no cumulation-size limit; the existing HTTP/3 limits (maxHeaderListSize, maxUnknownFramePayloadLength, DEFAULT_MAX_FIELD_SECTION_SIZE) are not applied to this handler. A remote, unauthenticated peer with an established HTTP/3 connection to a default Netty HTTP/3 server can declare a very large literal length and then trickle fewer bytes than declared, causing the ByteToMessageDecoder MERGE cumulator to retain and grow the per-connection buffer, and ultimately triggering a large byte-array allocation. This leads to unbounded per-connection heap growth and OutOfMemoryError, resulting in denial of service. Fixed in 4.2.18.Final.","status":"published","published":"2026-09-26T14:16:00Z","modified":"2026-10-17T12:58:41.595420548Z","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","level":"high"}],"updated_at":"2026-11-02T16:55:58.519486Z"}]}}