CVE-2026-11941
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedCloudflare Quiche was affected by 2 use-after-free vulnerabilities in the connection ID iterator FFI functions. The “quiche_connection_id_iter_next” and “quiche_conn_retired_scid_next” functions would return a pointer to a “ConnectionId” to the applications via function arguments, but the owned “ConnectionId” would be dropped at the end of those functions' scope. Only applications using those FFI functions are affected. The FFI API is disabled by default by a build-time feature flag. Impact If unpatched, an application calling the affected FFI functions will dereference freed memory. The most likely outcome is undefined behavior leading to a process crash (denial of service). Depending on allocator state, the read may also return adjacent heap contents, resulting in limited information disclosure or incorrect connection identifier handling. Mitigation Users are requested to upgrade to quiche 0.29.2 which is the earliest version containing the fix for this issue.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceCloudflare Quiche contains use-after-free vulnerabilities in two FFI functions (quiche_connection_id_iter_next and quiche_conn_retired_scid_next) that return pointers to ConnectionId objects that are dropped at the end of the function scope, allowing callers to dereference freed memory.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify if quiche is usedReview project dependencies (Cargo.toml for Rust, package.json, requirements.txt, or build configuration) to see if cloudflare/quiche is listed as a dependency. Check for linked library binaries or crates that depend on quiche.Affected if quiche is present as a dependency or linked library
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Determine quiche versionRun `cargo tree -p quiche` to see the installed version, or check the Cargo.lock file for the quiche entry. If using a binary, check the library version via `ldd` or dependency info.Affected if version is lower than 0.29.2
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Check if FFI feature is enabledInspect the build configuration or Cargo.toml to see if the `ffi` feature flag is enabled for quiche. Look for `default = ["ffi"]` or `features = ["ffi"]` in the quiche dependency section. Check build scripts or compile-time flags.Affected if FFI feature is explicitly enabled in the build configuration
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Verify usage of vulnerable FFI functionsSearch source code for calls to `quiche_connection_id_iter_next` or `quiche_conn_retired_scid_next` functions from the FFI bindings. These are C-compatible FFI exports from the quiche library.Affected if code calls either of these two specific FFI functions
User is affected if they use quiche version below 0.29.2, have the FFI feature enabled in their build, and actively call either quiche_connection_id_iter_next or quiche_conn_retired_scid_next in their code.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade to quiche version 0.29.2 or later. Applications not using the FFI API are not affected since it is disabled by default via build-time feature flag.
quiche 0.29.2
- Check current quiche version in use (e.g., via Cargo.toml, package manager, or build logs)
- Upgrade quiche dependency to version 0.29.2 or later
- Rebuild/recompile the application to link against the fixed library version
- If using FFI functions, retest application to confirm the use-after-free is resolved
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-11941 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-11941 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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