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no cvss —

CVE-2026-88823 json

AES-GCM-SIV AAD Forgery After Zero-length Incremental AAD Update

published yesterday modified yesterday also EUVD-2026-121609

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

Issue summary: The AES-GCM-SIV implementation treats a zero-length Additional Authenticated Data (AAD) update as a reset of all the AAD supplied so far, instead of leaving the AAD unchanged. An application that supplies its AAD in several fragments, one of which is empty, therefore produces or verifies messages whose authentication tag does not cover the AAD supplied before the empty fragment.

Impact summary: Data an application intended to authenticate alongside a message is silently left unauthenticated. An attacker can forge the AAD of such a message.

CWE: CWE-325: Missing Cryptographic Step

Description: An application passing AAD in multiple chunks of which some have zero length will have the previous AAD chunks effectively unauthenticated. Also, on context re-initialisation, the AAD was not reset, which meant that any AAD accumulated from the previous context usage were also included in the AAD of the new message.

The fix makes a zero-length AAD update a no-op and clears any accumulated AAD whenever the context is re-initialised with a key or a nonce. A re-initialisation that only changes parameters keeps the AAD.

FIPS impact: no The FIPS modules are not affected, as AES-GCM-SIV is not a FIPS approved algorithm and is implemented only in the default provider, outside the OpenSSL FIPS module boundary.

Patch / fix

  • OpenSSL OpenSSL 3.5.10, 4.0.4, 4.1.1

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Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-11).

Affected products

  • OpenSSL OpenSSL

Classification

Weakness
  • CWE-325 Missing Cryptographic Step
Technology feeds

References

Sources

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