xfrm: fix sk_dst_cache double-free in xfrm_user_policy()
CVSS score
7.8
EPSS probability
%0.1
Risk score
0.0
Published
2 mo ago
Kanıt listesindeki ürün ve sürüm eşleşmesini kontrol edin; bazı varyantlar hâlâ etkileniyor olabilir.
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Vulnerability description
CVE AI research
DayBreach AI Explanation
Verified against sourcesSources read
1
Source agreement
Tam uyum
Evidence confidence
%50
Short explanation
CVE-2026-64581 is a use-after-free vulnerability in the Linux xfrm module due to improper handling of sk_dst_cache during policy changes. It is exploitable via unprivileged user in user+network namespace. Patch status is UNKNOWN. No active exploitation reported by CISA KEV.
This vulnerability allows unprivileged users to trigger use-after-free in kernel memory, potentially leading to privilege escalation or code execution. It affects widely deployed Linux systems and requires timely patching due to the lack of reliable patch status.
What should be done?
- Follow vendor advisories for specific version ranges.
- No reliable patch status available; verify via official Linux kernel releases.
- Ensure kernel version is updated to a version post-affected range.
The sources give limited detail on some technical conditions. Review the chain of evidence below before deciding how to act.
Chain of evidence and sources
CVE-2026-64581, Linux çekirdeğinin xfrm modülünde, politika değişikliklerinde sk_dst_cache'daki iki kez boşaltma sorunu nedeniyle dst_release'da use-after-free oluşabilir. Bu, kullanıcı+network namespace üzerinden ve yetkisiz erişimle kullanılabilir.
Bu ele geçirme, 96b678d08268b5f5c6fc99d4289d9b7e334fc683 ve diğer belirtilen sürümler öncesi olan Linux çekirdeği sürümlerine etki eder; yama durumu bilinmiyor.
CISA KEV'ye göre bu ele geçirme aktif istismar edilmiyor ve herhangi bir açık kaynak PoC veya istismar bulunmamaktadır.
Show the technical text from the sources
In the Linux kernel, the following vulnerability has been resolved: xfrm: fix sk_dst_cache double-free in xfrm_user_policy() xfrm_user_policy() clears the socket dst cache with __sk_dst_reset(), i.e. the non-atomic __sk_dst_set(sk, NULL): it reads sk_dst_cache with rcu_dereference_protected(), stores NULL and dst_release()s the old dst. That is only safe if no other thread modifies sk_dst_cache concurrently. For a connected UDP socket that does not hold: the transmit fast path (udp_sendmsg -> sk_dst_check -> sk_dst_reset) resets the cache locklessly with an atomic xchg(). A per-socket policy change racing a send can make both sides observe the same old dst and each dst_release() it, dropping the socket's single reference twice and freeing the xfrm_dst bundle while it is still referenced: BUG: KASAN: slab-use-after-free in dst_release Write of size 4 at addr ffff88801897b6c0 by task exploit/155 Call Trace: ... dst_release (... ./include/linux/rcuref.h:109) xfrm_user_policy (./include/net/sock.h:2239 ./include/net/sock.h:2256 net/xfrm/xfrm_state.c:3053) do_ip_setsockopt (net/ipv4/ip_sockglue.c:1347) ip_setsockopt (net/ipv4/ip_sockglue.c:1417) do_sock_setsockopt (net/socket.c:2368) __sys_setsockopt (net/socket.c:2393) __x64_sys_setsockopt (net/socket.c:2396) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Reachable by an unprivileged user via a user+network namespace. Use the atomic sk_dst_reset() so the cache is cleared and released with a single xchg(): whichever side wins releases the dst once, the other sees NULL and does nothing. Behaviour is otherwise unchanged.
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Explanation produced with the local qwen3:4b-instruct model. Numerical metrics and the KEV, patch and exploit statuses are not determined by AI.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-64581 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 7.8 | CVSS V31 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | NVD |
| 7.8 | CVSS V3_1 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | CVE CNA |
| 5.1 | CVSS 3.x | — | CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H | Microsoft MSRC |
Patch and Remediation Guide
Solution & Remediation Advisory
2 düzeltme kanıtı bulundu; en az 4 ürün veya sürüm hâlâ etkileniyor ya da inceleniyor.
7.1.6-1Debian sid: 7.1.6-1
Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-64581 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-64581 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
Similar Vulnerabilities
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