AZL-99552
See a problem?- Import Source
- https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-99552.json
- JSON Data
- https://api.test.osv.dev/v1/vulns/AZL-99552
- Upstream
- Published
- 2026-09-04T16:18:05Z
- Modified
- 2026-09-23T14:17:43Z
- Summary
- CVE-2026-80793 affecting package kernel 6.6.152.1-1
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
ipv4: reject undersized MTUs in ip_do_fragment()
ip_do_fragment() subtracts the IPv4 header length from the effective MTU and passes the resulting payload MTU to ip_frag_next().
If the effective MTU is smaller than hlen + 8, ip_frag_next() rounds the fragment payload length down to zero. The fragmentation state then never makes forward progress: state->left, state->ptr and state->offset stay unchanged while ip_do_fragment() keeps allocating and transmitting header-only fragments until the softlockup detector fires.
This is reproducible with a route installed using "mtu lock 20", but it is also reproducible without route MTU lock, for example by forwarding a packet to a device whose MTU is 20.
Fix it in ip_do_fragment() by rejecting mtu < hlen + 8 with -EMSGSIZE, matching the existing IPv6 fragmentation check.
- References