CVE-2026-53239: linux Use After Free
Vulnerability summary
CVE-2026-53239 is a high (CVSS 7.8) Use After Free vulnerability in linux. EPSS estimates a 0.13% chance of exploitation in the next 30 days, higher than 2.4% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 49 · Related 37Timeline
- 25-06-2026PublishedVulnerability first disclosed.
- 19-10-2026Last modifiedVulnerability information updated.
Description
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
CVSS metrics
6 scores · 5 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- OSV · ChainguardEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- NVDNIST7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.13%
Chance of exploitation in the next 30 days
Percentile
2%
Versus all other CVEs
30-day change
0.00 pp
From 0.13% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
- CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
Affected systems
Ubuntu164 products
- linuxAll versions (No fix recorded) | < 5.15.0-198.208 | < 6.8.0-146.146 | < 7.0.0-31.31
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.15.0-1117.124 | < 6.8.0-1066.69 | < 7.0.0-1012.12
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Chainguard6 products
- linux-azure-6.18< 6.18.38-r0
- linux-gcp-6.18< 6.18.38-r0
- linux-gcp-6.18-bootc-boot-installed< 6.18.38-r0
- linux-qemu-6.18< 6.18.38-r0
- linux-qemu-6.18-bootc-boot-installed< 6.18.38-r0
Linux2 products
- linux≥ 6be3b0db6db82cf056a72cc18042048edd27f8ee, < 8fc536e9f6856230f19c7d13e71af064b6a77b22 | ≥ 6be3b0db6db82cf056a72cc18042048edd27f8ee, < c4c1ea36d83bf3c4569468ca5b8b614fda1bf821 | ≥ 6be3b0db6db82cf056a72cc18042048edd27f8ee, < 25c8c7fb3b0b9668c7d05e209f58c158d2b020c7 | ≥ 6be3b0db6db82cf056a72cc18042048edd27f8ee, < 42827d03f8009a6a218bacab153e21f39d6a121c | ≥ 6be3b0db6db82cf056a72cc18042048edd27f8ee, < 88697cf980222d5906a37bf47662dac0732e2a0f | ≥ 6be3b0db6db82cf056a72cc18042048edd27f8ee, < b5316e2b8614a87d8736941972441cb47bfd4491 | ≥ 6be3b0db6db82cf056a72cc18042048edd27f8ee, < ec82ea4eb220164d854f8734ca5a35e23e577b94 | ≥ 6be3b0db6db82cf056a72cc18042048edd27f8ee, < 7f2d76c9c03257c0782afef9d95321fa04096f60 | 5.0
- linux_kernel≥ 5.0, < 5.10.259 | ≥ 5.11, < 5.15.210 | ≥ 5.16, < 6.1.176 | ≥ 6.2, < 6.6.143 | ≥ 6.7, < 6.12.94 | ≥ 6.13, < 6.18.36 | ≥ 6.19, < 7.0.13 | 7.1:rc1 | 7.1:rc2 | 7.1:rc3 | 7.1:rc4 | 7.1:rc5 | 7.1:rc6 | 7.1:rc7
Debian1 product
- linux< 6.1.176-1 | < 6.12.94-1 | < 7.0.13-1
4 vendors · 173 products
