AZL-99552
See a problem?- Import Source
- https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-99552.json
- JSON Data
- https://api.osv.dev/v1/vulns/AZL-99552
- Upstream
- Published
- 2026-09-04T16:18:05Z
- Modified
- 2026-09-05T14:17:04.550132200Z
- Summary
- CVE-2026-80793 affecting package kernel 6.6.150.1-1
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
ipv4: reject undersized MTUs in ipdofragment()
ipdofragment() subtracts the IPv4 header length from the effective MTU and passes the resulting payload MTU to ipfragnext().
If the effective MTU is smaller than hlen + 8, ipfragnext() 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 ipdofragment() 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 ipdofragment() by rejecting mtu < hlen + 8 with -EMSGSIZE, matching the existing IPv6 fragmentation check.
- References