VulnerabilityPublished 27 Jul 2026Updated 30 Jul 2026

CVE-2026-64551: Linux kernel · sctp: validate STALE_COOKIE cause length before reading staleness

Source GCVE Database

Authoritative record:CVE-2026-64551· Critical 9.1

Not known to be exploited · CVSS 9.1 Critical · fixed in ebe0a55d954fa8da383b6192edb8f763dcb002d5 : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

9.1Critical

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in ebe0a55d954fa8da383b6192edb8f763dcb002d5, bbd6b2ea966cf57b6ae095cf5a8dbc993cd197a0, a257b41ddfe9e327b26581ad2777f04b23ac73f5 +5

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-m58p-8fjh-3whj

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < ebe0a55d954fa8da383b6192edb8f763dcb002d5	Fixed in ebe0a55d954fa8da383b6192edb8f763dcb002d5
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < bbd6b2ea966cf57b6ae095cf5a8dbc993cd197a0	Fixed in bbd6b2ea966cf57b6ae095cf5a8dbc993cd197a0
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < a257b41ddfe9e327b26581ad2777f04b23ac73f5	Fixed in a257b41ddfe9e327b26581ad2777f04b23ac73f5
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 588706ebaf8cdb4a4161602949eba365514b1db1	Fixed in 588706ebaf8cdb4a4161602949eba365514b1db1
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 6022da37786701df1fc5dd946a6dcba59d5473b1	Fixed in 6022da37786701df1fc5dd946a6dcba59d5473b1
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 861f884f5471632c731cbbd612a1c072e391a624	Fixed in 861f884f5471632c731cbbd612a1c072e391a624

AI-suggested

If you cannot patch yet, restrict access to raw SCTP sockets to trusted users to prevent unprivileged processes from exploiting this vulnerability.

Description

A critical vulnerability in the Linux kernel SCTP implementation allows an unprivileged peer to leak uninitialized kernel memory. The flaw occurs when processing an ERROR chunk with a STALE_COOKIE cause in the COOKIE_ECHOED state, where the kernel reads beyond the intended cause length, potentially leaking sensitive data. This memory leak can be triggered by any peer capable of driving an association into COOKIE_ECHOED, including unprivileged processes using raw SCTP sockets. The vulnerability has been resolved by validating the STALE_COOKIE cause length before reading the staleness field and discarding causes that are too short.

Impact

An attacker can leak uninitialized kernel memory contents remotely without privileges, potentially exposing sensitive information. The vulnerability does not affect integrity but impacts confidentiality and availability due to the kernel reading out-of-bounds memory and possible kernel instability. The CVSS vector indicates network attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, high confidentiality impact, no integrity impact, and high availability impact.

Summary

The Linux kernel SCTP subsystem improperly reads a 4-byte Measure of Staleness field following a STALE_COOKIE cause header in an ERROR chunk during the COOKIE_ECHOED state. The code incorrectly reads from the first cause in the chunk rather than the STALE_COOKIE cause, which may be shorter than expected. This leads to out-of-bounds reads past the cause or even past the skb tail, leaking uninitialized kernel memory to the peer in the Cookie Preservative of the reply INIT. The vulnerability is reachable by any peer that can drive an association into COOKIE_ECHOED, including unprivileged users with raw SCTP socket access. The fix involves checking the length of the STALE_COOKIE cause before reading and discarding causes that are too short.

References

Community reviews

Loading reviews…