Debian LinuxOperating system · Debian
CVE-2024-36971
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 · uneditedIn the Linux kernel, the following vulnerability has been resolved: net: fix __dst_negative_advice() race __dst_negative_advice() does not enforce proper RCU rules when sk->dst_cache must be cleared, leading to possible UAF. RCU rules are that we must first clear sk->sk_dst_cache, then call dst_release(old_dst). Note that sk_dst_reset(sk) is implementing this protocol correctly, while __dst_negative_advice() uses the wrong order. Given that ip6_negative_advice() has special logic against RTF_CACHE, this means each of the three ->negative_advice() existing methods must perform the sk_dst_reset() themselves. Note the check against NULL dst is centralized in __dst_negative_advice(), there is no need to duplicate it in various callbacks. Many thanks to Clement Lecigne for tracking this issue. This old bug became visible after the blamed commit, using UDP sockets.
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 confidenceA race condition in the Linux kernel's __dst_negative_advice() function allows Use-After-Free (UAF) by not following proper RCU rules. The code clears the dst_cache and releases the old dst in the wrong order, which became exploitable after a specific commit when using UDP sockets.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Debian LinuxOperating system
= 10.0
Linux KernelOperating system
>= 4.6, < 4.19.316>= 4.20, < 5.4.278>= 5.5, < 5.10.219>= 5.11, < 5.15.161>= 5.16, < 6.1.94>= 6.2, < 6.6.34>= 6.7, < 6.9.4CVSS 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
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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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Check running kernel versionRun `uname -r` or `cat /proc/version` to obtain the exact kernel version stringAffected if The version falls within any of these ranges: >= 4.6 to < 4.19.316, >= 4.20 to < 5.4.278, >= 5.5 to < 5.10.219, >= 5.11 to < 5.15.161, >= 5.16 to < 6.1.94, >= 6.2 to < 6.6.34, or >= 6.7 to < 6.9.4
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Verify the negative_advice callback implementationCheck if the kernel source file containing __dst_negative_advice() or the respective ->negative_advice() callbacks (such as in ipv4/route.c or similar) calls sk_dst_reset() instead of directly manipulating sk->dst_cache followed by dst_releaseAffected if The source code still uses the old pattern in __dst_negative_advice() where dst_release() is called before clearing sk->dst_cache, rather than each callback calling sk_dst_reset() itself
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Confirm network usage triggers the code pathMonitor for network operations that invoke __dst_negative_advice(), such as routing lookups with negative caching or failed connection attempts that trigger the negative_advice callbackAffected if The system performs network operations that exercise the dst_cache negative advice code path on a kernel version within the affected ranges
You are affected if your running kernel version falls within any of the listed vulnerable version ranges and the patch has not been applied to fix the RCU ordering in __dst_negative_advice().
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 · scoped4.19.3165.4.2785.10.219
Apply the kernel patch that enforces correct RCU ordering (clear sk->sk_dst_cache before calling dst_release), or update to a kernel version containing the fix.
Upgrade to kernel 4.19.316+, 5.4.278+, 5.10.219+, or 5.15.161+ (Debian 10.0 users should upgrade to a newer Debian release with supported kernel)
- 1. Identify the currently running kernel version using 'uname -r'
- 2. Check which kernel version family your current kernel belongs to (4.19.x, 5.4.x, 5.10.x, or 5.15.x)
- 3. Upgrade the Linux kernel to a fixed version: for 4.19.x line upgrade to 4.19.316 or later; for 5.4.x line upgrade to 5.4.278 or later; for 5.10.x line upgrade to 5.10.219 or later; for 5.15.x line upgrade to 5.15.161 or later
- 4. On Debian 10.0, update the kernel package via 'apt-get update && apt-get install linux-image-<version>' or by running 'apt-get dist-upgrade'
- 5. Reboot the system to load the patched kernel
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Debian Linux
Exploited in the wild — priority engagement
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2024-36971 — 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-2024-36971 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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