CVE-2026-74550 net: do not send ICMP/NDISC Redirects when peer allocation fails
Attackers can trigger un-rate-limited ICMP/NDISC Redirect storms when peer allocation fails, causing denial of service in the Linux kernel.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74550?
CVE-2026-74550 is a high-severity denial of service vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-74550?
How do I fix CVE-2026-74550?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-74550 being exploited?
There is no known exploitation of CVE-2026-74550 in the wild and no public exploit code.
Sources
Also known as AZL-96495, BELL-CVE-2026-74550, DEBIAN-CVE-2026-74550, GHSA-9cch-cjjm-3m2c, UBUNTU-CVE-2026-74550.