Bug 2521481 (CVE-2026-74724)

Summary: CVE-2026-74724 kernel: ipvs: avoid out-of-bounds write in ip_vs_nat_icmp
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's IPVS (IP Virtual Server) component. A local attacker can exploit this vulnerability by manipulating packets processed by IPVS, specifically within the `ip_vs_nat_icmp` function. This manipulation can lead to an out-of-bounds write due to improper handling of the IP header length field. This allows the attacker to write data beyond the intended memory area, potentially corrupting data or leading to further system compromise.
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Description OSIDB Bzimport 2026-08-22 15:47:40 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ipvs: avoid out-of-bounds write in ip_vs_nat_icmp

Sashiko warns that local attacker can modify the packet
while it is processed by IPVS. Some places read the
IP ihl field multiple times which can cause out-of-bounds
access. One such place is ip_vs_nat_icmp where we
can write after the validated area.

Fix it by providing ciph argument just like it is done for
IPv6 and use ciph->len as offset to the embedded transport
header.

Modify some IPv4 header checks by reading the ihl field
only once.
Comment 1 Keith Grant 2026-08-24 18:28:52 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082240-CVE-2026-74724-1dbc@gregkh/T