CVE-2026-5265

Description

When generating an ICMP Destination Unreachable or Packet Too Big response, the handler copies a portion of the original packet into the ICMP error body using the IP header's self-declared total length (ip_tot_len for IPv4, ip6_plen for IPv6) without validating it against the actual packet buffer size. A VM can send a short packet with an inflated IP length field that triggers an ICMP error (e.g., by hitting a reject ACL), causing ovn-controller to read heap memory beyond the valid packet data and include it in the ICMP response sent back to the VM.

CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H

EPSS — Exploit Prediction

0.0009

Probability of exploitation

0.25%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-130 CWE-130

References

Other References

https://access.redhat.com/errata/RHSA-2026:11694 https://access.redhat.com/errata/RHSA-2026:11695 https://access.redhat.com/errata/RHSA-2026:11696 https://access.redhat.com/errata/RHSA-2026:11698 https://access.redhat.com/errata/RHSA-2026:11700 https://access.redhat.com/errata/RHSA-2026:11701 https://access.redhat.com/errata/RHSA-2026:11702 https://access.redhat.com/security/cve/CVE-2026-5265 https://bugzilla.redhat.com/show_bug.cgi?id=2453458 http://www.openwall.com/lists/oss-security/2026/04/20/2

Frequently Asked Questions

What is CVE-2026-5265? +

When generating an ICMP Destination Unreachable or Packet Too Big response, the handler copies a portion of the original packet into the ICMP error body using the IP header's self-declared total length (ip_tot_len for IPv4, ip6_plen for IPv6) without validating it against the actual packet buffer size. A VM can send a short packet with an inflated IP length field that triggers an ICMP error (e.g., by hitting a reject ACL), causing ovn-controller to read heap memory beyond the valid packet data and include it in the ICMP response sent back to the VM. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-5265? +

CVE-2026-5265 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0009, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-5265? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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