VulnerabilityPublished 1 May 2026Updated 3 May 2026

CVE-2026-31719: Linux kernel · crypto: krb5enc – fix async decrypt skipping hash verification

Source GCVE Database

Authoritative record:CVE-2026-31719· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in e51f42114abbdf47f29dda43e7826be28907fcd2 : patch Linux kernel soon.

Data as of 27 Oct 2026, 01:01 UTC

CVSS 3.1 base score

7.5High

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

Patch: Available – fixed in e51f42114abbdf47f29dda43e7826be28907fcd2, 07cbb1bd424370671814a862913c99a6e1441588, 3bfbf5f0a99c991769ec562721285df7ab69240b

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

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

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: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 1 May 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-774g-v4gm-8h6v

What to do

Upgrade Linux kernel to e51f42114abbdf47f29dda43e7826be28907fcd2, 07cbb1bd424370671814a862913c99a6e1441588 or 3bfbf5f0a99c991769ec562721285df7ab69240b.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ d1775a177f7f38156d541c8a3e3c91eaa6e69699, < e51f42114abbdf47f29dda43e7826be28907fcd2	Fixed in e51f42114abbdf47f29dda43e7826be28907fcd2
LinuxLinux	Affected ≥ d1775a177f7f38156d541c8a3e3c91eaa6e69699, < 07cbb1bd424370671814a862913c99a6e1441588	Fixed in 07cbb1bd424370671814a862913c99a6e1441588
LinuxLinux	Affected ≥ d1775a177f7f38156d541c8a3e3c91eaa6e69699, < 3bfbf5f0a99c991769ec562721285df7ab69240b	Fixed in 3bfbf5f0a99c991769ec562721285df7ab69240b
LinuxLinux	Affected =6.15	Fixed in–

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel by adding an intermediate callback to ensure hash verification is performed on asynchronous decrypt completion and by correcting error handling of EBUSY and EINPROGRESS codes. Users should apply the official Linux kernel updates that include this fix. No other mitigation steps are indicated.

Description

CVE-2026-31719 is a vulnerability in the Linux kernel's krb5enc crypto module where asynchronous decryption skips hash verification, leading to bypass of integrity checks. This occurs because the async decrypt callback directly signals completion without performing the hash check, unlike the encrypt path which correctly chains callbacks. The issue also involves improper handling of EBUSY and EINPROGRESS error codes. The vulnerability has been fixed by introducing an intermediate callback to ensure hash verification is performed on async decrypt completion and correcting error handling.

Impact

The vulnerability allows asynchronous decrypt operations in the krb5enc crypto module to bypass integrity verification (hash checks), which can lead to acceptance of tampered or corrupted data without detection. This compromises data integrity but does not affect confidentiality or availability. The CVSS score of 7.5 (high) reflects the significant integrity impact with network attack vector and no required privileges or user interaction.

Summary

The Linux kernel's krb5enc_dispatch_decrypt() function sets the asynchronous skcipher completion callback to the caller's own completion handler, which causes the hash verification step (krb5enc_dispatch_decrypt_hash()) to be skipped when the decrypt operation completes asynchronously. This bypasses integrity verification, potentially allowing tampered data to be accepted. The encrypt path uses an intermediate callback (krb5enc_encrypt_done) to ensure hash computation is performed after async completion. The fix adds a similar intermediate callback (krb5enc_decrypt_done) for decrypt operations to chain into the hash verification. Additionally, the patch corrects handling of EBUSY and EINPROGRESS error codes by removing krb5enc_request_complete(), which improperly swallowed EINPROGRESS notifications, and adding missing EBUSY checks in the encrypt callback. The fix also unsets the MAY_BACKLOG flag on the async completion path to prevent repeated EINPROGRESS notifications to users.

CWE-354Improper Validation of Integrity Check Value (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product does not validate or incorrectly validates the integrity check values or "checksums" of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission.
Implementation
Ensure that the checksums present in messages are properly checked in accordance with the protocol specification before they are parsed and used.
OWASP Cheat Sheets
XML Security (opens in a new tab)
REST Security (opens in a new tab)
JSON Web Token for Java (opens in a new tab)
OWASP ASVS 4.0.3
V11.1.7 (opens in a new tab)
V13.3.2 (opens in a new tab)
V3.5.3 (opens in a new tab)
Attack patterns
Checksum Spoofing (opens in a new tab)
Padding Oracle Crypto Attack (opens in a new tab)
Manipulating Writeable Configuration Files (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Oct 2026, 01:01 UTC

WeaknessesCWE-354

Technical details

References

Community reviews

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