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CVE-2026-88823

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

Exploited
No known exploitation
Fix
Fixed in 4.1.1, 4.0.4, 3.5.10
Who is exposed
Not reported

Do first: Upgrade to a fixed version: 4.1.1, 4.0.4, 3.5.10.

Published
Last modified
Reference
Last checked
21/100 · provisional
Low (openssl)
None on Exploit-DB, Metasploit or GitHub

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

Show the full description

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.

cve.now Index

21Pcve.now Index 21 of 100 · methodology v3 · provisional
  • Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
  • Exposure?/25Unknown. No advisory context yet
  • Reach20/20Affects OpenSSL (software on nearly every server, desktop or phone)
  • Severity1/10Rated low by openssl
  • No patch0/5No signal

What would change the score

  • Would score about 76 if added to CISA KEV
  • Would score about 71 if CISA's SSVC rates exploitation active
  • Would score about 43 if advisories confirm default setups are exposed

How the score works · Rankings

What to do

  • Upgrade to a fixed version: 4.1.1, 4.0.4, 3.5.10.

Check your systems with an agent

Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.

Check whether my systems are affected by CVE-2026-88823 (AES-GCM-SIV AAD Forgery After Zero-length Incremental AAD Update), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-88823 (entry last updated 2026-11-10):
Affected:
- OpenSSL OpenSSL: from 4.1.0, fixed in 4.1.1; from 4.0.0, fixed in 4.0.4; from 3.5.0, fixed in 3.5.10
Fixed versions: 4.1.1, 4.0.4, 3.5.10.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-88823 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-88823 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://openssl-library.org/news/secadv/20261110.txt
- https://github.com/openssl/openssl/commit/6747b1a278816dd7db46438040a70b0b5e5e0a90
- https://github.com/openssl/openssl/commit/2f5fc833ff9b5bfe00b32f8b5c74f73c5773c682
- https://github.com/openssl/openssl/commit/159e1de0c448d7b9f09ad768c8e141def4aa1eb4
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-88823
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-88823.

Timeline

  1. CVE published
  2. First seen by cve.now

Affected versions

  • OpenSSL OpenSSL

    From 4.1.0 · fixed in 4.1.1; From 4.0.0 · fixed in 4.0.4; From 3.5.0 · fixed in 3.5.10

Evidence 6

CVE record · 2

Establishes: The identifier and description.

  1. Record
  2. Record

Other links · 4

  1. Advisory
  2. Patch
  3. Patch
  4. Patch

Corrections

None so far.

Something wrong on this page? Report an error. Every fix is listed here.

Questions about CVE-2026-88823

Is CVE-2026-88823 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data

Which versions are affected by CVE-2026-88823?

OpenSSL: from 4.1.0 before 4.1.1; from 4.0.0 before 4.0.4; from 3.5.0 before 3.5.10.Source: cve.now feed data

How do I fix CVE-2026-88823?

Upgrade to a fixed version: 4.1.1, 4.0.4, 3.5.10.Source: cve.now feed data

Sources

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