CVE-2026-43500: rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present

Vulnerability summary

CVE-2026-43500 is a high (CVSS 7.8) Out-of-bounds Write vulnerability in linux. EPSS estimates a 94.12% chance of exploitation in the next 30 days, higher than 99.8% of scored vulnerabilities. 4 public exploits are recorded.

Timeline

1. 11-05-2026
   PublishedVulnerability first disclosed.
2. 01-09-2026
   Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present The DATA-packet handler in rxrpc_input_call_event() and the RESPONSE handler in rxrpc_verify_response() copy the skb to a linear one before calling into the security ops only when skb_cloned() is true. An skb that is not cloned but still carries externally-owned paged fragments (e.g. SKBFL_SHARED_FRAG set by splice() into a UDP socket via __ip_append_data, or a chained skb_has_frag_list()) falls through to the in-place decryption path, which binds the frag pages directly into the AEAD/skcipher SGL via skb_to_sgvec(). Extend the gate to also unshare when skb_has_frag_list() or skb_has_shared_frag() is true. This catches the splice-loopback vector and other externally-shared frag sources while preserving the zero-copy fast path for skbs whose frags are kernel-private (e.g. NIC page_pool RX, GRO). The OOM/trace handling already in place is reused.

• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.
• CWE-123Write-what-where ConditionAny condition where the attacker has the ability to write an arbitrary value to an arbitrary location, often as the result of a buffer overflow.