CVE-2024-40624: TorrentPier Deserialization of Untrusted Data vulnerability

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 1.0%, percentile 62: FIRST’s model estimates a 1.0% chance of exploitation activity in the next 30 days, higher than 62% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes torrentpier/torrentpier (Composer (PHP)) <= 2.4.3, fixed in 2.4.4. Check your lockfile, including transitive dependencies.

What it is

TorrentPier is an open source BitTorrent Public/Private tracker engine, written in php. In torrentpier/library/includes/functions.php, gettracks() uses the unsafe native PHP serialization format to deserialize user-controlled cookies. One can use phpggc and the chain Guzzle/FW1 to write PHP code to an arbitrary file, and execute commands on the system. For instance, the cookie bbt will be deserialized when browsing to viewforum.php. This issue has been addressed in commit ed37e6e52 which is expected to be included in release version 2.4.4. Users are advised to upgrade as soon as the new release is available. There are no known workarounds for this vulnerability.

From the GitHub advisory

Summary

In torrentpier/library/includes/functions.php, gettracks() uses the unsafe native PHP serialization format to deserialize user-controlled cookies:

https://github.com/torrentpier/torrentpier/blob/84f6c9f4a081d9ffff4c233098758280304bf50f/library/includes/functions.php#L41-L60

PoC

One can use phpggc and the chain Guzzle/FW1 to write PHP code to an arbitrary file, and execute commands on the system. For instance, the cookie bbt will be deserialized when browsing to viewforum.php.

Weakness type: CWE-502.

Product: torrentpier/torrentpier (Composer (PHP)) · Assigned by: GitHub_M · Published: 2024-07-15

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.00% probability of exploitation activity in the next 30 days; percentile 62.

Timeline

• 2024-07-15 — CVE record published by GitHub_M
• 2024-07-15 — GitHub-reviewed advisory GHSA-fg86-4c2r-7wxw published (critical)
• 2024-08-02 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-fg86-4c2r-7wxw github.com
2. CVE.org record CVE-2024-40624 cve.org
3. NVD entry CVE-2024-40624 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com

Critical Composer (PHP) advisories · Today’s Security Digest