# CVE-2026-78655: Punk::Plugin::TOTP versions before 0.05 for Perl allow the second-factor attempt limit to be reset by replaying an earlier session cookie be

> Attackers can bypass TOTP attempt limits by replaying session cookies, allowing unlimited second-factor guesses if server-side session storage is not configured.

- **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:** No
- **Published:** 25 Aug 2026
- **Updated:** 26 Aug 2026
- **Also known as:** GHSA-vwg8-cr9j-895f

## What is CVE-2026-78655?

CVE-2026-78655 is a critical vulnerability, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Punk::Plugin::TOTP versions before 0.05 for Perl allow the second-factor attempt limit to be reset by replaying an earlier session cookie because the challenge route counts failures in the session.

The POST handler on challenge_path keeps the failure count as tries inside the totp_pending record in the session, raising it on each rejected code and deleting the pending record once it reaches attempts, five by default. Punk::Session carries the session in a signed cookie unless the application declares a store, and keeps no server-side record, so an earlier value of the same session stays valid until the expiry stamped inside it. A client that saves the cookie before its failed attempts and presents it again gets the pending record back with its counter, and the limit never fires. The replayed record is accepted while its own expiry, pending_ttl seconds from the challenge and 300 by default, has not passed.

Sessions declared with a store are not affected: the pending record and its counter then live server-side.

The attempt limit does not bound guessing of the second factor, which is left to the per-address rate limit the plugin registers on the same path, 30 requests per 60 seconds.

Weakness: CWE-642 (External Control of Critical State Data), CWE-307 (Improper Restriction of Excessive Authentication Attempts)

## Which versions are affected by CVE-2026-78655?


## How do I fix CVE-2026-78655?

No fix has been published for CVE-2026-78655 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-78655 being exploited?

There is no known exploitation of CVE-2026-78655 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-78655 and fix it if it is affected.

What it is: CVE-2026-78655 is a critical vulnerability, 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-2026-78655 in the wild and no public exploit code.

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-2026-78655/ (Markdown: https://insights.sbomify.com/CVE-2026-78655/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-78655
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-78655
- OSV: https://osv.dev/vulnerability/CVE-2026-78655

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-78655/
Summaries are generated and may contain mistakes; the official description above is the record.