Linux Kernel: RXRPC Skb Misuse Causes Failed Challenge Serial Comparison
CVE-2026-31640 Published on April 24, 2026
rxrpc: Fix use of wrong skb when comparing queued RESP challenge serial
In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix use of wrong skb when comparing queued RESP challenge serial
In rxrpc_post_response(), the code should be comparing the challenge serial
number from the cached response before deciding to switch to a newer
response, but looks at the newer packet private data instead, rendering the
comparison always false.
Fix this by switching to look at the older packet.
Fix further[1] to substitute the new packet in place of the old one if
newer and also to release whichever we don't use.
Products Associated with CVE-2026-31640
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Affected Versions
Linux:- Version 5800b1cf3fd8ccab752a101865be1e76dac33142 and below 9132b1a7bf83b4a8042fffbc99d075b727a16742 is affected.
- Version 5800b1cf3fd8ccab752a101865be1e76dac33142 and below 20386e7f8d97475b8d815873e246423317ec4260 is affected.
- Version 5800b1cf3fd8ccab752a101865be1e76dac33142 and below b33f5741bb187db8ff32e8f5b96def77cc94dfca is affected.
- Version 6.16 is affected.
- Before 6.16 is unaffected.
- Version 6.18.23, <= 6.18.* is unaffected.
- Version 6.19.13, <= 6.19.* is unaffected.
- Version 7.0, <= * is unaffected.