# CVE-2021-22901: curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed memory being used when a TLS 1.3 session t


- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 11 Jun 2021
- **Updated:** 14 Oct 2026
- **Also known as:** ALPINE-CVE-2021-22901, AZL-6360, CLEANSTART-2026-HL90171, CURL-CVE-2021-22901, GHSA-vjwf-ghhc-2p8q

## What is CVE-2021-22901?

CVE-2021-22901 is a high-severity vulnerability in Haxx Curl, published on 11 Jun 2021. 

### Official description

curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed memory being used when a TLS 1.3 session ticket arrives over a connection. A malicious server can use this in rare unfortunate circumstances to potentially reach remote code execution in the client. When libcurl at run-time sets up support for TLS 1.3 session tickets on a connection using OpenSSL, it stores pointers to the transfer in-memory object for later retrieval when a session ticket arrives. If the connection is used by multiple transfers (like with a reused HTTP/1.1 connection or multiplexed HTTP/2 connection) that first transfer object might be freed before the new session is established on that connection and then the function will access a memory buffer that might be freed. When using that memory, libcurl might even call a function pointer in the object, making it possible for a remote code execution if the server could somehow manage to get crafted memory content into the correct place in memory.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2021-22901?

It affects 26 products.


Products: Haxx Curl, Netapp Active Iq Unified Manager, Netapp Cloud Backup, Netapp H300e Firmware, Netapp H300s Firmware, Netapp H410s Firmware, Netapp H500e Firmware, Netapp H500s Firmware, Netapp H700e Firmware, Netapp H700s Firmware, Netapp Hci Compute Node Firmware, Netapp Oncommand Insight, Netapp Oncommand Workflow Automation, Netapp Snapcenter, Netapp Solidfire\, Enterprise Sds \& Hci Storage Node, Netapp Solidfire \& Hci Management Node, Netapp Solidfire Baseboard Management Controller Firmware, Oracle Communications Cloud Native Core Binding Support Function, Oracle Communications Cloud Native Core Network Function Cloud Native Environment, Oracle Communications Cloud Native Core Network Repository Function and 6 more.

## How do I fix CVE-2021-22901?

Upgrade to a fixed version.

## Is CVE-2021-22901 being exploited?

There is no known exploitation of CVE-2021-22901 in the wild and no public exploit code.

## Other vulnerabilities in Haxx Curl

- [CVE-2026-19931](https://insights.sbomify.com/CVE-2026-19931/): Negotiate ambient user conn reuse (critical 9.8)
- [CVE-2026-10536](https://insights.sbomify.com/CVE-2026-10536/): HTTP/2 stream-dependency tree UAF (critical 9.8)
- [CVE-2026-11856](https://insights.sbomify.com/CVE-2026-11856/): cross-origin Digest auth state leak (critical 9.8)
- [CVE-2026-8925](https://insights.sbomify.com/CVE-2026-8925/): SASL double-free (critical 9.8)
- [CVE-2026-9079](https://insights.sbomify.com/CVE-2026-9079/): stale proxy password leak (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-22901 and fix it if it is affected.

What it is: CVE-2021-22901 is a high-severity vulnerability in Haxx Curl, published on 11 Jun 2021. 
Exploitation: There is no known exploitation of CVE-2021-22901 in the wild and no public exploit code.

Affected product: Haxx Curl. 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-2021-22901/ (Markdown: https://insights.sbomify.com/CVE-2021-22901/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-22901
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-22901
- OSV: https://osv.dev/vulnerability/CVE-2021-22901

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-22901/
Summaries are generated and may contain mistakes; the official description above is the record.