# CVE-2026-63074: CMP Indefinite Cache Growth of ExtraCerts

> A malicious client can cause unbounded memory growth in OpenSSL CMP servers by flooding them with rejected messages containing unique extra certificates.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **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:** 25 Aug 2026
- **Also known as:** ALPINE-CVE-2026-63074, AZL-97881, AZL-97944, BELL-CVE-2026-63074, CLEANSTART-2026-BP03068, DEBIAN-CVE-2026-63074, ECHO-8298-2fc4-74d4, GHSA-2q27-mpm9-44m4, MINI-33pj-h8vc-qj7p, MINI-fhrr-mmfj-2cmj, UBUNTU-CVE-2026-63074

## What is CVE-2026-63074?

CVE-2026-63074 is a medium-severity denial of service 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: The OpenSSL Certificate Management Protocol (CMP) caches
additional certificates (extraCerts) sent in a CMP message, but never expunges
them (for instance if they are invalid).  If a server reuses an OSSL_CMP_CTX
frequently, this cache of extraCerts may grow unboundedly, and a malicious
client may flood a CMP server with requests driving this growth.

Impact summary: Users utilizing a CMP server that reuses a single OSSL_CMP_CTX
for the lifetime of a server process may observe unbounded memory growth in the
event a malicious client repeatedly sends requests containing unique extra
certificates, which may lead to OOM conditions.

CWE: CWE-770: Allocation of Resources Without Limits or Throttling

Description: If a remote user sends CMP messages to a server with a list of
extraCerts and the message is rejected, the extraCerts from the message remains
in the server contexts untrusted certificate stack.  This exposes servers with
long lived ctx objects to Denial of Service attacks in which an attacker sends
messages intending to be rejected with a large list of additional certificates
repeatedly, forcing the server to store them indefinitely.
   
The issue was fixed by removing the added extra certs if the message is
rejected, using the same method as when the context is configured to not do
caching at all.

FIPS impact: no
As the CMP code lives outside the FIPS module boundary, no FIPS
modules are affected by this CVE.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-63074?

It affects 1 product.


Products: Openssl Openssl.

## How do I fix CVE-2026-63074?

Apply the vendor's patch.

## Is CVE-2026-63074 being exploited?

There is no known exploitation of CVE-2026-63074 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-2026-63074 and fix it if it is affected.

What it is: CVE-2026-63074 is a medium-severity denial of service 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-2026-63074 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-2026-63074/ (Markdown: https://insights.sbomify.com/CVE-2026-63074/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63074
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63074
- OSV: https://osv.dev/vulnerability/CVE-2026-63074

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63074/
Summaries are generated and may contain mistakes; the official description above is the record.