CVE Intelligence
Medium Memory corruption

CVE-2025-21638 — sctp: sysctl: auth_enable: avoid using current->nsproxy

In the Linux kernel, the following vulnerability has been resolved: sctp: sysctl: auth_enable: avoid using current->nsproxy As mentioned in a previous commit of this series, using the 'net' structure via 'current' is not recommended for different reasons: - Inconsistency: getting info from the reader's/writer's netns vs only from the opener's netns. - current->nsproxy can be NULL in some cases, resulting in an 'Oops' (null-ptr-deref), e.g. when the current task is exiting, as spotted by syzbot [1] using acct(2). The 'net' structure can be obtained from the table->data using container_of(). Note that table->data could also be used directly, but that would increase the size of this fix, while 'sctp.ctl_sock' still needs to be retrieved from 'net' structure.

Published Jan 19, 2025 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.2% (30-day exploitation probability)+2
  • Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.24%
ahead of 14% of scored CVEs · Oct 15, 2026
Affects
Linux
Linux and 1 more
CVSS base
5.5
Medium · 4 source(s)
Prioritization reference: 7.1 provisional

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
  2. Apply the fixed version or the patch documented under Remediation.
  3. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux ≥ b14878ccb7fac0242db82720b784ab62c467c0dc and < cf387cdebfaebae228dfba162f94c567a67610c3version 3.15≥ 3.14.5 and < 3.15≥ 3.12.21 and < 3.13≥ 3.10.41 and < 3.11version 3938b0336a93fa5faa242dc9e5823ac69df9e066version 88830f227a1f96e44d82ddfcb0cc81d517ec6dd8version e5eae4a0511241959498b180fa0df0d4f1b11b9c
and 6 more ≥ b14878ccb7fac0242db82720b784ab62c467c0dc and < 15649fd5415eda664ef35780c2013adeb5d9c695≥ b14878ccb7fac0242db82720b784ab62c467c0dc and < c184bc621e3cef03ac9ba81a50dda2dae6a21d36≥ b14878ccb7fac0242db82720b784ab62c467c0dc and < 7ec30c54f339c640aa7e49d7e9f7bbed6bd42bf6≥ b14878ccb7fac0242db82720b784ab62c467c0dc and < 1b67030d39f2b00f94ac1f0af11ba6657589e4d3≥ b14878ccb7fac0242db82720b784ab62c467c0dc and < bd2a2939423566c654545fa3e96a656662a0af9e≥ b14878ccb7fac0242db82720b784ab62c467c0dc and < dc583e7e5f8515ca489c0df28e4362a70eade382
Vulnerable CVE Program (cve.org) e CISA ADP
Linux Linux Kernel ≥ 3.10.41 and < 3.11version 6.13-rc6version 6.13-rc5version 6.13-rc4version 6.13-rc3version 6.13-rc2version 6.13-rc1≥ 6.7 and < 6.12.10
and 6 more ≥ 6.2 and < 6.6.72≥ 5.16 and < 6.1.125≥ 5.11 and < 5.15.177≥ 5.5 and < 5.10.234≥ 3.14.5 and < 5.4.290≥ 3.12.20 and < 3.13
Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
7.1 CVSS 3.1 High 1.8 5.2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database
7.1 CVSS 3.1 High — — Linux via CVE Program (cve.org) e CISA ADP
5.5 CVSS 3.1 Medium 1.8 3.6 nvd@nist.gov via NIST National Vulnerability Database
5.5 CVSS 3.1 Medium — — GitHub, Inc. via GitHub Security Advisories
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 7.1 (416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-476 · NULL Pointer Dereference

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · linux/linux
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 15, 2026
  • Fix documented
    Oct 15, 2026 · NIST National Vulnerability Database
  • Affected products added · linux/linux kernel
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVSS changed · 5.5
    Oct 15, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · Alertas do Telegram
  • 2025
  • CVE published
    Jan 19, 2025 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 15, 2026 – Oct 15, 2026
  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

13 on the record

Elsewhere on this site

Linux
every CVE for this vendor
Memory corruption
same class
CWE-476
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-99999 ipv4: validate checksum_start before completing checksum 13h
  • CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 13h
  • CVE-2026-98431 RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency 1d
  • CVE-2026-98430 RDMA/efa: Keep admin queues alive while IRQ is registered 1d
  • CVE-2026-98429 RDMA/efa: Keep EQ resources alive while IRQ is registered 1d
  • CVE-2026-98428 ALSA: usb: 6fire: Avoid embedded URBs 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2025-21638 is "sctp: sysctl: auth_enable: avoid using current->nsproxy", rated Medium. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.5 describes technical severity. EPSS 0.24% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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