7.8

CVE-2026-31665: linux Use After Free

CVSS: 7.8v3.1HighModified
AliasesUBUNTU-CVE-2026-31665DEBIAN-CVE-2026-31665
Published 24-04-2026Last modified 19-10-2026
Open JSON

Vulnerability summary

CVE-2026-31665 is a high (CVSS 7.8) Use After Free vulnerability in linux. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7% of scored vulnerabilities.

Overall risk
31/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.8/10
010
High · v3.1 (CVE.org)
EPSS score
0.18%
0%100%
Low · +0.06 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 40 · Related 38
MGASA-2026-0108MGASA-2026-0110OPENSUSE-SU-2026:21388-1SUSE-SU-2026:22433-1SUSE-SU-2026:22436-1SUSE-SU-2026:22458-1

Timeline

  1. 24-04-2026
    PublishedVulnerability first disclosed.
  2. 19-10-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_ct: fix use-after-free in timeout object destroy nft_ct_timeout_obj_destroy() frees the timeout object with kfree() immediately after nf_ct_untimeout(), without waiting for an RCU grace period. Concurrent packet processing on other CPUs may still hold RCU-protected references to the timeout object obtained via rcu_dereference() in nf_ct_timeout_data(). Add an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer freeing until after an RCU grace period, matching the approach already used in nfnetlink_cttimeout.c. KASAN report: BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0 Read of size 4 at addr ffff8881035fe19c by task exploit/80 Call Trace: nf_conntrack_tcp_packet+0x1381/0x29d0 nf_conntrack_in+0x612/0x8b0 nf_hook_slow+0x70/0x100 __ip_local_out+0x1b2/0x210 tcp_sendmsg_locked+0x722/0x1580 __sys_sendto+0x2d8/0x320 Allocated by task 75: nft_ct_timeout_obj_init+0xf6/0x290 nft_obj_init+0x107/0x1b0 nf_tables_newobj+0x680/0x9c0 nfnetlink_rcv_batch+0xc29/0xe00 Freed by task 26: nft_obj_destroy+0x3f/0xa0 nf_tables_trans_destroy_work+0x51c/0x5c0 process_one_work+0x2c4/0x5a0

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.18%

Chance of exploitation in the next 30 days

Percentile

7%

Versus all other CVEs

30-day change

+0.06 pp

From 0.12% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.18%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu153 products
  • linuxAll versions (No fix recorded) | < 5.15.0-186.196 | < 6.8.0-136.136
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 5.15.0-1112.119 | < 6.8.0-1061.64
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < c458fc1c278a65ad5381083121d39a479973ebed | ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < c581e5c8f2b59158f62efe61c1a3dc36189081ff | ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < f16fe84879a5280f05ebbcea593a189ba0f3e79a | ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < 070abdf1b04325b21a20a2a0c39a2208af107275 | ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77 | ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < b42aca3660dc2627a29a38131597ca610dc451f9 | ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < d0983b48c10d1509fd795c155f8b1e832e1369ff | ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < f8dca15a1b190787bbd03285304b569631160eda | 4.19
  • linux_kernelEOL≥ 4.19.1, < 5.10.253 | ≥ 5.11, < 5.15.203 | ≥ 5.16, < 6.1.169 | ≥ 6.2, < 6.6.135 | ≥ 6.7, < 6.12.82 | ≥ 6.13, < 6.18.23 | ≥ 6.19, < 6.19.13 | 4.19 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3 | 7.0:rc4 | 7.0:rc5 | 7.0:rc6 | 7.0:rc7
Debian1 product
  • linux< 6.1.170-1 | < 6.12.85-1 | < 6.19.13-1

3 vendors · 156 products

References

43 links
Show all 43 references