# CVE-2026-75803: AEAD Forgeries with Empty Ciphertext When Using EVP_Cipher()

> Attackers can forge messages using ChaCha20-Poly1305 or AES-OCB with empty ciphertexts, bypassing authentication tag verification in OpenSSL.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Aug 2026
- **Updated:** 1 Sep 2026
- **Also known as:** ALPINE-CVE-2026-75803, AZL-97671, AZL-97884, AZL-97935, BELL-CVE-2026-75803, CLEANSTART-2026-JP03196, DEBIAN-CVE-2026-75803, ECHO-f836-71cf-434b, GHSA-vr27-9w4v-hjw2, MINI-44jf-8phr-j393, MINI-fp3v-939x-cv3j, RHSA-2026:59260, RHSA-2026:62786, ROOT-OS-ALPINE-317-CVE-2026-75803, UBUNTU-CVE-2026-75803, USN-8678-3

## What is CVE-2026-75803?

CVE-2026-75803 is a critical vulnerability in Openssl Openssl, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Issue summary: ChaCha20-Poly1305 and AES-OCB decryption with an empty
ciphertext can report success without verifying the supplied authentication
tag when the operation is finalized by calling the EVP_Cipher() function.

Impact summary: Applications calling EVP_Cipher() on an empty ciphertext and
expecting the call to check the AEAD tag may accept forged messages.

CWE: CWE-354 (Improper Validation of Integrity Check Value)

Description: The EVP_Cipher() API call for AEAD ciphers behaves like a one
shot encryption and decryption call. It also verifies the AEAD tag after the
decryption operation. However for AES-OCB and ChaCha20-Poly1305 ciphers
it skipped the AEAD tag verification when an empty ciphertext was passed to
the function. The callers of this function might believe that a successful
return indicates a valid AEAD tag for these ciphers, even when that has not
truly been validated in this case.

FIPS impact: no
The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this CVE
as the affected algorithms are not FIPS approved and thus not implemented
in the FIPS module.

Weakness: CWE-354 (Improper Validation of Integrity Check Value)

## Which versions are affected by CVE-2026-75803?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `bootupd` | Red Hat:hummingbird:1 | All versions | 0:0.2.36-3.hum1 |
| `ruby3.4` | Red Hat:hummingbird:1 | All versions | 0:3.4.10-31.7.hum1 |
| `ruby3.4-bundled-gems` | Red Hat:hummingbird:1 | All versions | 0:3.4.10-31.7.hum1 |
| `ruby3.4-default-gems` | Red Hat:hummingbird:1 | All versions | 0:3.4.10-31.7.hum1 |
| `ruby3.4-devel` | Red Hat:hummingbird:1 | All versions | 0:3.4.10-31.7.hum1 |
| `ruby3.4-doc` | Red Hat:hummingbird:1 | All versions | 0:3.4.10-31.7.hum1 |
| `ruby3.4-libs` | Red Hat:hummingbird:1 | All versions | 0:3.4.10-31.7.hum1 |
| `rust-bootupd` | Red Hat:hummingbird:1 | All versions | 0:0.2.36-3.hum1 |

Products: Openssl Openssl.

## How do I fix CVE-2026-75803?

Apply the vendor's patch.

## Is CVE-2026-75803 being exploited?

There is no known exploitation of CVE-2026-75803 in the wild and no public exploit code.

## Other vulnerabilities in Openssl Openssl

- [CVE-2009-3245](https://insights.sbomify.com/CVE-2009-3245/): Null dereference in n/a (critical 10.0)
- [CVE-2006-3738](https://insights.sbomify.com/CVE-2006-3738/): Memory corruption in n/a (critical 10.0)
- [CVE-2026-63073](https://insights.sbomify.com/CVE-2026-63073/): Untrusted Sender DN Used as Format String in CMP Response Validation (critical 9.8)
- [CVE-2016-6309](https://insights.sbomify.com/CVE-2016-6309/): Use after free in n/a (critical 9.8)
- [CVE-2016-0799](https://insights.sbomify.com/CVE-2016-0799/): Integer overflow in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-75803 and fix it if it is affected.

What it is: CVE-2026-75803 is a critical vulnerability in Openssl Openssl, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-75803 in the wild and no public exploit code.

Affected product: Openssl Openssl. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-75803/ (Markdown: https://insights.sbomify.com/CVE-2026-75803/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-75803
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-75803
- OSV: https://osv.dev/vulnerability/CVE-2026-75803

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-75803/
Summaries are generated and may contain mistakes; the official description above is the record.