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CVE Record

CVE-2025-40182: crypto: skcipher - Fix reqsize handling

In the Linux kernel, the following vulnerability has been resolved: crypto: skcipher - Fix reqsize handling Commit afddce13ce81d ("crypto: api - Add reqsize to crypto_alg") introduced cra_reqsize field in crypto_alg struct to replace type specific reqsize fields. It looks like this was introduced specifically for ahash and acomp from the commit description as subsequent commits add necessary changes in these alg frameworks. However, this is being recommended for use in all crypto algs [1] instead of setting reqsize using crypto_*_set_reqsize(). Using cra_reqsize in skcipher algorithms, hence, causes memory corruptions and crashes as the underlying functions in the algorithm framework have not been updated to set the reqsize properly from cra_reqsize. [2] Add proper set_reqsize calls in the skcipher init function to properly initialize reqsize for these algorithms in the framework. [1]: https://lore.kernel.org/linux-crypto/aCL8BxpHr5OpT04k@gondor.apana.org.au/ [2]: https://gist.github.com/Pratham-T/24247446f1faf4b7843e4014d5089f6b

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel crypto bookkeeping error can use an incorrect request-memory size for some symmetric-key cipher operations. This can corrupt kernel memory and crash the system; the CVSS assessment also indicates potential confidentiality and integrity loss. Exploitation requires local, low-privileged access, so this is serious but not described as remotely reachable.

Executive priority

Treat this as a high-priority kernel maintenance issue, especially where untrusted users can run local code. Patch through normal distributor channels after confirming branch applicability. It is below emergency remote-code-execution urgency because the supplied vector requires local access and no source reports active exploitation.

Technical view

After cra_reqsize was added to crypto_alg, skcipher initialization did not transfer that value through the required setter path. Algorithms using cra_reqsize could receive incorrectly sized request contexts, causing memory corruption and crashes. The fixes add set_reqsize calls during initialization. CVSS 3.1 is 7.8: local, low-complexity, low-privilege, and no user interaction.

Likely exposure

Exposure is limited to Linux builds carrying the faulty reqsize change and skcipher implementations relying on it. The affected-version data lists 6.16, 6.17.4, 6.18, and an ambiguous “0”; exact distributor backport status is not provided. The CVSS vector requires local low-privileged access.

Exploitation context

No cited source reports active exploitation, and the bundle marks KEV false. Public evidence documents memory corruption and crashes, but does not demonstrate reliable privilege escalation or data theft. The local, low-complexity vector makes systems allowing untrusted local code more concerning.

Researcher notes

Scope depends on algorithms using cra_reqsize before skcipher initialization was corrected. The bundle provides two stable commits but does not map them to distribution packages or branches. No CWE is assigned. Memory corruption and crashes are documented; reliable privilege escalation or data theft is not demonstrated by the supplied evidence.

Mitigation direction

  • Apply a distributor kernel update containing the applicable skcipher reqsize fix.
  • Confirm vendor guidance maps the correct stable fix to each deployed kernel branch.
  • Until patched, reduce untrusted local access where operationally feasible.

Validation and detection

  • Inventory running kernel versions and distributor package revisions across Linux systems.
  • Compare kernel provenance with afddce13ce81d and the two supplied stable fix commits.
  • Confirm updated builds contain the branch-appropriate fix before closing remediation.
  • Review kernel logs for crypto-related memory corruption, oopses, or crashes.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2025-40182 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
3Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2025-40182Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxafddce13ce81d52a13898fa0700917835c71acd6, afddce13ce81d52a13898fa0700917835c71acd6unaffected
LinuxLinux6.16, 0, 6.17.4, 6.18affected
Weakness

CWE details

No CWE listed

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