Bug 2516966 (CVE-2026-74550)

Summary: CVE-2026-74550 kernel: net: do not send ICMP/NDISC Redirects when peer allocation fails
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
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 kernel. When the network stack fails to allocate a peer entry, it can send un-rate-limited Internet Control Message Protocol (ICMP) or Neighbor Discovery (NDISC) Redirect messages. This can be exploited by a remote attacker to cause an uncontrolled flood of network traffic, leading to a Denial of Service (DoS) condition.
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Description OSIDB Bzimport 2026-08-15 12:41:29 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net: do not send ICMP/NDISC Redirects when peer allocation fails

When inet_getpeer_v4() or inet_getpeer_v6() fails to allocate a peer entry
under memory pressure or tree size caps, redirect handlers previously fell
back to sending un-rate-limited ICMP/NDISC Redirect messages.

In IPv4, ip_rt_send_redirect() called icmp_send() directly when peer == NULL.
In IPv6, ip6_forward() and ndisc_send_redirect() passed a NULL peer into
inet_peer_xrlim_allow(), which returned true when peer == NULL.

Because ICMP/NDISC Redirects are not part of the default global rate limit
mask (sysctl_icmp_ratemask), sending redirects when peer == NULL creates
an un-rate-limited ICMP packet storm.

Fix this by failing closed in ip_rt_send_redirect(), ip6_forward(), and
ndisc_send_redirect() when peer is NULL.
Comment 1 gkamathe 2026-08-21 07:11:58 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081550-CVE-2026-74550-27c9@gregkh/T