CVE-2026-43500
EPSS 0.0%Vendor patches + distro advisories + "in-the-wild" claim; no public PoC confirmed; metadata gaps limit scoring higher.
What: Linux kernel local privilege escalation (LPE) in rxrpc and ESP4/ESP6 networking modules allowing unprivileged-to-root escalation; part of "Dirty Frag" vulnerability chain (CVE-2026-43284 + CVE-2026-43500).
Why it matters: Multiple major distributions (AlmaLinux, Debian, Gentoo, RedHat, Unraid) have issued urgent security advisories and kernel patches within days of disclosure. Social chatter explicitly cites active in-the-wild exploitation. Defenders are triaging mitigation steps (module removal, cache drops). No PoC code linked in supplied posts, but vendor response velocity and exploit-in-wild claims suggest operational risk.
Where it's seen: Coordinated French-language technical writeup generating engagement; vendor security advisories across distros; system administrators discussing immediate patching and module-disable workarounds; security practitioners sharing detection/mitigation steps.
RISK: CRITICAL — Linux LPE, multi-distro patches, active exploitation claimed, impacts NAS and server infrastructure.
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.