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Advisory severityHigh7.0Vendor: MediumRed Hat Linux

High [CVE-2026-53239] fix use-after-free on inexact bin in xfrm_policy_bysel_ctx

This high-severity Red Hat Linux advisory covers CVE-2026-53239 affecting Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support, Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-53239 Source published Source updated

VulniPulse record published Record updated

CVE-2026-53239
Affected products & platforms
Red Hat LinuxLinux Kernel
Open source advisory

Summary

In the Linux kernel, the following vulnerability has been resolved: xfrm: policy: fix use-after-free on inexact bin in xfrm_policy_bysel_ctx() Fix the race by pruning the bin while still holding xfrm_policy_lock, before dropping it. Use __xfrm_policy_inexact_prune_bin() directly since the lock is already held.

The wrapper xfrm_policy_inexact_prune_bin() becomes unused and is removed.

Race: CPU0 (XFRM_MSG_DELPOLICY) CPU1 (XFRM_MSG_NEWSPDINFO) ========================== ========================== xfrm_policy_bysel_ctx(): spin_lock_bh(xfrm_policy_lock) bin = xfrm_policy_inexact_lookup() __xfrm_policy_unlink(pol) spin_unlock_bh(xfrm_policy_lock) xfrm_policy_kill(ret) // wide window, lock not held xfrm_hash_rebuild(): spin_lock_bh(xfrm_policy_lock) __xfrm_policy_inexact_flush(): kfree_rcu(bin) // bin freed spin_unlock_bh(xfrm_policy_lock) xfrm_policy_inexact_prune_bin(bin) // UAF: bin is freed A race condition exists in the `xfrm` policy handling, specifically within the `xfrm_policy_bysel_ctx()` function.

This flaw allows for a use-after-free vulnerability, where memory is accessed after it has been released. This can lead to system instability or a denial of service (DoS), making the system unresponsive or causing it to crash.

Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-364.

Is CVE-2026-53239 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-53239 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-53239?

Upgrade to a fixed release named by Red Hat:

  • kernel-0:6.12.0-211.55.1.el10_2
  • kernel-0:6.12.0-55.108.1.el10_0
  • kernel-rt-0:4.18.0-553.164.1.rt7.505.el8_10
  • kernel-0:4.18.0-553.164.1.el8_10
  • kernel-0:4.18.0-305.211.1.el8_4
  • kernel-0:4.18.0-372.220.1.el8_6
  • kernel-0:4.18.0-477.172.1.el8_8
  • kernel-0:5.14.0-687.49.1.el9_8
  • kernel-0:5.14.0-284.197.1.el9_2
  • kernel-rt-0:5.14.0-284.197.1.rt14.482.el9_2
  • kernel-0:5.14.0-427.154.1.el9_4
  • kernel-0:5.14.0-570.146.1.el9_6

12 more fixed releases are listed below.

Confirm against the vendor advisory before you patch.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.

Official advisory · high-confidence parse· fetched 15 days ago·verify at source

Fixed versions
  • kernel-0:6.12.0-211.55.1.el10_2
  • kernel-0:6.12.0-55.108.1.el10_0
  • kernel-rt-0:4.18.0-553.164.1.rt7.505.el8_10
  • kernel-0:4.18.0-553.164.1.el8_10
  • kernel-0:4.18.0-305.211.1.el8_4
  • kernel-0:4.18.0-372.220.1.el8_6
  • kernel-0:4.18.0-477.172.1.el8_8
  • kernel-0:5.14.0-687.49.1.el9_8
  • kernel-0:5.14.0-284.197.1.el9_2
  • kernel-rt-0:5.14.0-284.197.1.rt14.482.el9_2
  • kernel-0:5.14.0-427.154.1.el9_4
  • kernel-0:5.14.0-570.146.1.el9_6
  • RHSA-2026:67471
  • RHSA-2026:75560
  • RHSA-2026:68532
  • RHSA-2026:68531
  • RHSA-2026:77217
  • RHSA-2026:77216
  • RHSA-2026:77301
  • RHSA-2026:68570
  • RHSA-2026:80908
  • RHSA-2026:82860
  • RHSA-2026:77218
  • RHSA-2026:74174

Official advisory · high-confidence parse· fetched 15 days ago·verify at source

Mitigation

Upgrade to a fixed release: kernel-0:6.12.0-211.55.1.el10_2, kernel-0:6.12.0-55.108.1.el10_0, kernel-rt-0:4.18.0-553.164.1.rt7.505.el8_10, kernel-0:4.18.0-553.164.1.el8_10, kernel-0:4.18.0-305.211.1.el8_4, kernel-0:4.18.0-372.220.1.el8_6. That is the remediation for this advisory.

The vendor advisory may list interim mitigations or workarounds not captured here. Review it before change work.

Official advisory · high-confidence parse· fetched 15 days ago·verify at source

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