QID 357029

Date Published: 2024-01-24

QID 357029: Amazon Linux Security Advisory for kernel : ALAS2023-2024-493

When a router encounters an ipv6 packet too big to transmit to the next-hop, it returns an icmp6 "packet too big" (ptb) message to the sender.
The sender caches this updated maximum transmission unit (mtu) so it knows not to exceed this value when subsequently routing to the same host. in linux kernels prior to 6.3, garbage collection is run on the ipv6 destination route cache if the number of entries exceeds a threshold when adding the destination to the cache.
This garbage collection examines every entry in the cache while holding a lock.
In these affected kernel versions, a flood of the ipv6 icmp6 ptb messages could cause high lock contention and increased cpu usage, leading to a denial-of-service. the fix backports the garbage collection improvements from linux kernel 6.3 by bringing the ipv6 code closer to the ipv4 code, which does not have this issue.
Patch: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=af6d10345ca76670c1b7c37799f0d5576ccef277 (cve-2023-52340)



Note: The preceding description block is extracted directly from the security advisory. Using automation, we have attempted to clean and format it as much as possible without introducing additional issues.

Successful exploitation of this vulnerability could lead to a securitybreach or could affect integrity, availability, and confidentiality.

  • CVSS V3 rated as Critical - 8.6 severity.
  • CVSS V2 rated as Medium - 5.4 severity.
    • Solution
    Please refer to Amazon advisory: ALAS2023-2024-493 for affected packages and patching details, or update with your package manager.
    Vendor References

    CVEs related to QID 357029

    CVE-2023-52340 |
    Software Advisories
    Advisory ID Software Component Link
    ALAS2023-2024-493 amazon linux 2023 URL Logo alas.aws.amazon.com/AL2023/ALAS-2024-493.html
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