# CVE-2026-77358: cpp-httplib: Use-after-free of TLS session in WebSocketClient::shutdown_and_close()

> A use-after-free in cpp-httplib's TLS WebSocket client allows attackers to cause crashes or potentially execute code during connection teardown.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Aug 2026
- **Updated:** 31 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-77358, GHSA-w7p7-f35j-mw7q, OESA-2026-3800, OESA-2026-3801, OESA-2026-3961, UBUNTU-CVE-2026-77358

## What is CVE-2026-77358?

CVE-2026-77358 is a high-severity use after free vulnerability in yhirose cpp-httplib, published on 27 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

cpp-httplib is a C++ header-only HTTP/HTTPS library. In versions 0.33.0 through 0.50.0, the TLS-enabled WebSocket client frees the TLS session before closing the WebSocket that still uses it, producing a use-after-free. In WebSocketClient::shutdown_and_close the SSL object is freed and the pointer cleared, but the subsequent WebSocket close still sends a close frame through the SSL socket stream, which holds a raw copy of the now-dangling session pointer and reads from and writes to the freed memory. The same freed-then-used ordering is reachable through the client's destructor and its connect path, so ordinary teardown of a secure WebSocket connection triggers the defect. This issue is fixed in version 0.50.1.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-77358?


## How do I fix CVE-2026-77358?

Upgrade to a fixed version.

## Is CVE-2026-77358 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77358 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-77358 and fix it if it is affected.

What it is: CVE-2026-77358 is a high-severity use after free vulnerability in yhirose cpp-httplib, published on 27 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77358 exists.

Affected product: yhirose cpp-httplib. 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-2026-77358/ (Markdown: https://insights.sbomify.com/CVE-2026-77358/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77358
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77358
- OSV: https://osv.dev/vulnerability/CVE-2026-77358

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-77358/
Summaries are generated and may contain mistakes; the official description above is the record.