Bug 2559696 (CVE-2026-99064)

Summary: CVE-2026-99064 kernel: cipso: adjust cached option offsets when removing CIPSO
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel. When removing Commercial IP Security Option (CIPSO) attributes from a network packet, the kernel does not adjust the cached offsets of subsequent IP options. A remote attacker could exploit this vulnerability by sending specially crafted IPv4 packets, causing the system to read incorrect packet data and copy it into fixed-size memory buffers. This flaw can result in memory corruption or a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-10-23 13:16:23 UTC 
In the Linux kernel, the following vulnerability has been resolved:

cipso: adjust cached option offsets when removing CIPSO

cipso_v4_skbuff_delattr() removes the CIPSO bytes but does not adjust
cached offsets for options that follow them.

For example, with a valid 10-byte CIPSO option followed by a seven-byte
RR option, parsing records rr at offset 30.  Removing CIPSO moves RR to
offset 20, while the cached offset remains 30.  Consumers such as
ip_forward_options() and __ip_options_echo() then access the wrong bytes;
the latter may interpret packet data as the option length and copy it into
fixed-size option storage.

Mirror cipso_v4_delopt() and subtract cipso_len from the srr, rr, ts and
router_alert offsets when they follow CIPSO.  cipso_len is the distance
the first memmove() shifts those options.  The later header move and
network-header reset relocate the bytes and their offset base together.
Comment 1 gkamathe 2026-10-27 04:07:44 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-99064.mbox