Bug 2492837 (CVE-2026-53151)

Summary: CVE-2026-53151 kernel: rxrpc: Fix the ACK parser to extract the SACK table for parsing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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 Linux kernel's AF_RXRPC subsystem. This vulnerability involves incorrect handling of fragmented UDP packets when parsing the SACK (Selective Acknowledgment) table. An attacker could potentially craft a fragmented UDP packet to trigger an incorrect buffer access within the kernel, which may lead to system instability or other undefined behavior.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-06-25 10:08:20 UTC 
In the Linux kernel, the following vulnerability has been resolved:

rxrpc: Fix the ACK parser to extract the SACK table for parsing

Fix modification of the received skbuff in rxrpc_input_soft_acks() and a
potential incorrect access of the buffer in a fragmented UDP packet (the
packet would probably have to be deliberately pre-generated as fragmented)
when AF_RXRPC tries to extract the contents of the SACK table by copying
out the contents of the SACK table into a buffer before attempting to parse

AF_RXRPC assumes that it can just call skb_condense() and then validly
access the SACK table from skb->data and that it will be a flat buffer -
but skb_condense() can silently fail to do anything under some
circumstances.

Note that whilst rxrpc_input_soft_acks() should be able to parse extended
ACKs, the rest of AF_RXRPC doesn't currently support that.

Further, there's then no need to call skb_condense() in rxrpc_input_ack(),
so don't.
Comment 1 TEJ RATHI 2026-06-26 06:47:54 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062547-CVE-2026-53151-4924@gregkh/T