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Fencer Intel
critical 9.8

CVE-2026-74434 in the critical feed json

rxrpc: Don't move a peeked OOB message onto the pending queue

published 2mo ago modified 2mo ago also EUVD-2026-59581

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

rxrpc: Don't move a peeked OOB message onto the pending queue

rxrpc_recvmsg_oob() takes a received oob message off recvmsg_oobq and, if a response is needed, moves it onto the pending_oobq tree. However, only the unlink from recvmsg_oobq is guarded by MSG_PEEK; the move onto pending_oobq always runs.

As a result, reading a challenge with MSG_PEEK leaves the skb on recvmsg_oobq while also adding it to pending_oobq. Since struct sk_buff's rbnode shares storage with its next and prev pointers, rb_insert_color() overwrites the list linkage, and the skb, which holds a single reference, becomes reachable from both queues at once.

When the socket is closed both queues are drained in turn. While draining recvmsg_oobq, __skb_unlink() follows the next and prev pointers that rbnode has overwritten and writes to a bad address. Also, as the skb holds a single reference but is freed from each queue, both the skb and the connection reference it holds are released twice. This leads to memory corruption and to a use-after-free caused by the connection refcount underflow.

MSG_PEEK does not consume the message from the queue, so only unlink it from recvmsg_oobq and then move it onto pending_oobq or free it when the message is actually consumed.

Patch / fix

  • Linux Linux 6.18.40, 7.1.5, 7.2
  • linux Debian 14 7.1.5-1

debian advisories DEBIAN-CVE-2026-74434

  • linux Ubuntu 26.04 LTS 7.0.0-34.34
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1013.13
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1013.13
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1007.8
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1014.14
  • linux-azure Ubuntu 26.04 LTS 7.0.0-1017.17
  • linux-raspi Ubuntu 26.04 LTS 7.0.0-1020.20
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-34.34.1

ubuntu advisories UBUNTU-CVE-2026-74434

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-74434 updated cvss 7.0

kernel: rxrpc: Don't move a peeked OOB message onto the pending queue

  • Red Hat Enterprise Linux 10 kernel
    affected: no fix available
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.