# CVE-2021-25981: Talkyard - Insufficient Session Expiration

> Attackers can reuse valid admin session tokens after logout to gain administrative privileges if they obtain the token via other means.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Jan 2022
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-4jw2-24wg-vcf7

## What is CVE-2021-25981?

CVE-2021-25981 is a critical authentication bypass vulnerability in debiki talkyard, published on 3 Jan 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In Talkyard, regular versions v0.2021.20 through v0.2021.33 and dev versions v0.2021.20 through v0.2021.34, are vulnerable to Insufficient Session Expiration. This may allow an attacker to reuse the admin’s still-valid session token even when logged-out, to gain admin privileges, given the attacker is able to obtain that token (via other, hypothetical attacks)

Weakness: CWE-613 (DEPRECATED: Insufficient Session Expiration)

## Which versions are affected by CVE-2021-25981?

It affects 1 product.


Products: Talkyard Talkyard.

## How do I fix CVE-2021-25981?

No fix has been published for CVE-2021-25981 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-25981 being exploited?

There is no known exploitation of CVE-2021-25981 in the wild and no public exploit code.

## Other vulnerabilities in debiki talkyard

- [CVE-2021-25980](https://insights.sbomify.com/CVE-2021-25980/): Talkyard - Host-Header Injection Leads to Account Takeover (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-25981 and fix it if it is affected.

What it is: CVE-2021-25981 is a critical authentication bypass vulnerability in debiki talkyard, published on 3 Jan 2022. 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-2021-25981 in the wild and no public exploit code.

Affected product: debiki talkyard. 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-2021-25981/ (Markdown: https://insights.sbomify.com/CVE-2021-25981/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-25981
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-25981
- OSV: https://osv.dev/vulnerability/CVE-2021-25981

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-25981/
Summaries are generated and may contain mistakes; the official description above is the record.