CVE-2026-62303
Pistache: DoS via stack exhaustion in REST router path normalization (regex_replace on long slash runs)
Pistache is a high-performance REST toolkit written in C++. From 0.0.5 through 0.4.26, SegmentTreeNode::sanitizeResource() in src/server/router.cc uses std::regex_replace() with the //+ expression to collapse consecutive slashes. With libstdc++, a path containing tens of thousands of consecutive slash characters can recurse deeply enough to exhaust the stack and crash the process. Router::route(), Router::addRoute() and Router::removeRoute() reach this normalization. Unauthenticated remote exploitation is conditional on a deployment allowing sufficiently long request paths, such as by increasing Endpoint::Options::maxRequestSize() above the default 4096-byte limit or forwarding long paths through a front end. Direct router API use is also affected when attacker-controlled route or resource strings reach the normalizer. Native builds reproduced a crash around 24,000 consecutive slashes, although the exact threshold depends on the stack and standard library; the demonstrated failure is stack exhaustion rather than uninitialized-memory use. A source fix replaces recursive regular-expression normalization with an iterative pass, but no containing repository release was verified as of time of publication.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
5.9
Pistache: DoS via stack exhaustion in REST router path normalization (regex_replace on long slash runs)
Pistache is a high-performance REST toolkit written in C++. From 0.0.5 through 0.4.26, SegmentTreeNode::sanitizeResource() in src/server/router.cc uses std::regex_replace() with the //+ expression to collapse consecutive slashes. With libstdc++, a path containing tens of thousands of consecutive slash characters can recurse deeply enough to exhaust the stack and crash the process. Router::route(), Router::addRoute() and Router::removeRoute() reach this normalization. Unauthenticated remote exploitation is conditional on a deployment allowing sufficiently long request paths, such as by increasing Endpoint::Options::maxRequestSize() above the default 4096-byte limit or forwarding long paths through a front end. Direct router API use is also affected when attacker-controlled route or resource strings reach the normalizer. Native builds reproduced a crash around 24,000 consecutive slashes, although the exact threshold depends on the stack and standard library; the demonstrated failure is stack exhaustion rather than uninitialized-memory use. A source fix replaces recursive regular-expression normalization with an iterative pass, but no containing repository release was verified as of time of publication.
- Record
CVE-2026-62303- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400, CWE-674
- Updated
- 2026-11-02
EUVDEUVD-2026-114262
5.9
Pistache is a high-performance REST toolkit written in C++. From 0.0.5 through 0.4.26, SegmentTreeNode::sanitizeResource() in src/server/router.cc uses std::regex_replace() with the //+ expression to collapse consecutive slashes. With libstdc++, a path containing tens of thousands of consecutive slash characters can recurse deeply enough to exhaust the stack and crash the process. Router::route(), Router::addRoute() and Router::removeRoute() reach this normalization. Unauthenticated remote exploitation is conditional on a deployment allowing sufficiently long request paths, such as by increasing Endpoint::Options::maxRequestSize() above the default 4096-byte limit or forwarding long paths through a front end. Direct router API use is also affected when attacker-controlled route or resource strings reach the normalizer. Native builds reproduced a crash around 24,000 consecutive slashes, although the exact threshold depends on the stack and standard library; the demonstrated failure is stack exhaustion rather than uninitialized-memory use. A source fix replaces recursive regular-expression normalization with an iterative pass, but no containing repository release was verified as of time of publication.
- Record
EUVD-2026-114262- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
NVD
5.9
Pistache is a high-performance REST toolkit written in C++. From 0.0.5 through 0.4.26, SegmentTreeNode::sanitizeResource() in src/server/router.cc uses std::regex_replace() with the //+ expression to collapse consecutive slashes. With libstdc++, a path containing tens of thousands of consecutive slash characters can recurse deeply enough to exhaust the stack and crash the process. Router::route(), Router::addRoute() and Router::removeRoute() reach this normalization. Unauthenticated remote exploitation is conditional on a deployment allowing sufficiently long request paths, such as by increasing Endpoint::Options::maxRequestSize() above the default 4096-byte limit or forwarding long paths through a front end. Direct router API use is also affected when attacker-controlled route or resource strings reach the normalizer. Native builds reproduced a crash around 24,000 consecutive slashes, although the exact threshold depends on the stack and standard library; the demonstrated failure is stack exhaustion rather than uninitialized-memory use. A source fix replaces recursive regular-expression normalization with an iterative pass, but no containing repository release was verified as of time of publication.
- Record
CVE-2026-62303- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400, CWE-674
- Updated
- 2026-11-02
OSV
5.9
Pistache: DoS via stack exhaustion in REST router path normalization (regex_replace on long slash runs)
Pistache is a high-performance REST toolkit written in C++. From 0.0.5 through 0.4.26, SegmentTreeNode::sanitizeResource() in src/server/router.cc uses std::regex_replace() with the //+ expression to collapse consecutive slashes. With libstdc++, a path containing tens of thousands of consecutive slash characters can recurse deeply enough to exhaust the stack and crash the process. Router::route(), Router::addRoute() and Router::removeRoute() reach this normalization. Unauthenticated remote exploitation is conditional on a deployment allowing sufficiently long request paths, such as by increasing Endpoint::Options::maxRequestSize() above the default 4096-byte limit or forwarding long paths through a front end. Direct router API use is also affected when attacker-controlled route or resource strings reach the normalizer. Native builds reproduced a crash around 24,000 consecutive slashes, although the exact threshold depends on the stack and standard library; the demonstrated failure is stack exhaustion rather than uninitialized-memory use. A source fix replaces recursive regular-expression normalization with an iterative pass, but no containing repository release was verified as of time of publication.
- Record
CVE-2026-62303- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400, CWE-674
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-62303
5.9
Pistache is a high-performance REST toolkit written in C++. From 0.0.5 through 0.4.26, SegmentTreeNode::sanitizeResource() in src/server/router.cc uses std::regex_replace() with the //+ expression to collapse consecutive slashes. With libstdc++, a path containing tens of thousands of consecutive slash characters can recurse deeply enough to exhaust the stack and crash the process. Router::route(), Router::addRoute() and Router::removeRoute() reach this normalization. Unauthenticated remote exploitation is conditional on a deployment allowing sufficiently long request paths, such as by increasing Endpoint::Options::maxRequestSize() above the default 4096-byte limit or forwarding long paths through a front end. Direct router API use is also affected when attacker-controlled route or resource strings reach the normalizer. Native builds reproduced a crash around 24,000 consecutive slashes, although the exact threshold depends on the stack and standard library; the demonstrated failure is stack exhaustion rather than uninitialized-memory use. A source fix replaces recursive regular-expression normalization with an iterative pass, but no containing repository release was verified as of time of publication.
- Record
DEBIAN-CVE-2026-62303- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-62303
5.9
Pistache is a high-performance REST toolkit written in C++. From 0.0.5 through 0.4.26, SegmentTreeNode::sanitizeResource() in src/server/router.cc uses std::regex_replace() with the //+ expression to collapse consecutive slashes. With libstdc++, a path containing tens of thousands of consecutive slash characters can recurse deeply enough to exhaust the stack and crash the process. Router::route(), Router::addRoute() and Router::removeRoute() reach this normalization. Unauthenticated remote exploitation is conditional on a deployment allowing sufficiently long request paths, such as by increasing Endpoint::Options::maxRequestSize() above the default 4096-byte limit or forwarding long paths through a front end. Direct router API use is also affected when attacker-controlled route or resource strings reach the normalizer. Native builds reproduced a crash around 24,000 consecutive slashes, although the exact threshold depends on the stack and standard library; the demonstrated failure is stack exhaustion rather than uninitialized-memory use. A source fix replaces recursive regular-expression normalization with an iterative pass, but no containing repository release was verified as of time of publication.
- Record
UBUNTU-CVE-2026-62303- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-05
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
pistacheDebian:12 |
All versions, plus listed versions 0.0.5+ds-30.0.5+ds-40.0.5+ds-50.0.5+ds-5.10.0.5+ds-5.1~exp10.4.26+ds-20.4.26+ds-3 |
None known |
pistacheDebian:13 |
All versions, plus listed versions 0.0.5+ds-5.10.4.26+ds-20.4.26+ds-3 |
None known |
pistacheDebian:14 |
All versions, plus listed versions 0.0.5+ds-5.10.4.26+ds-20.4.26+ds-3 |
None known |
pistacheUbuntu:24.04:LTS |
All versions, plus listed versions 0.0.5+ds-50.0.5+ds-5.10.0.5+ds-5.1build10.0.5+ds-5.1build2 |
None known |
pistacheUbuntu:26.04:LTS |
All versions, plus listed versions 0.4.26+ds-3 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, facts, references | OSV | |
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-62303 is a medium vulnerability (CVSS 5.9) in Pistacheio Pistache, published October 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.31%, the 23rd percentile. No source names a fixed version.
References
github.com/pistacheio/pistache/security/advisories/GHSA-q474-pqcp-gqm5
github.com/pistacheio/pistache/commit/935461352403696f3ca0dbb9a7de7d2609e7ce91
github.com/CVEProject/cvelistV5/tree/main/cves/2026/62xxx/CVE-2026-62303.json
nvd.nist.gov/vuln/detail/CVE-2026-62303
security-tracker.debian.org/tracker/CVE-2026-62303
ubuntu.com/security/CVE-2026-62303
cve.org/CVERecord?id=CVE-2026-62303