# CVE-2026-123096: anacrolix/torrent memory exhaustion in tracker HTTP

Source: https://junglewise.ai/threats/cve-2026-123096-anacrolix-torrent-through-1-61-0-contains-a-memory-exhaustion  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-05. Updated: 2026-11-05  
License: CC BY 4.0 with a link back

CVE-2026-123096 · Severity: medium · CVSS 6.5 · Published 2026-11-05

The anacrolix/torrent BitTorrent client library buffers HTTP responses from trackers without size limits, allowing a malicious tracker to crash client processes by returning extremely large or heavily compressed responses. An attacker controlling a tracker referenced in a torrent file or magnet link can exhaust a client's memory, causing a denial of service and disrupting file-sharing operations.

Technologies: [Anacrolix Torrent](https://junglewise.ai/threats/technologies/torrent). Vendors: [Anacrolix](https://junglewise.ai/threats/vendors/anacrolix).

## Quick answers

**Is CVE-2026-123096 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-123096 being exploited in the wild.

**How severe is CVE-2026-123096?** Medium severity, with a CVSS score of 6.5, published 5 November 2026.

**Which products and versions are affected?** Anacrolix Torrent through 1.61.0.

**Is there a fix for CVE-2026-123096?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-123096 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-123096?** Check whether you run Anacrolix Torrent at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in the tracker/http package's Client.Announce and Client.Scrape methods, which buffer unbounded HTTP responses without memory limits. Attackers can exploit this by returning oversized or gzip-compressed tracker responses that decompress to enormous sizes. The issue affects all versions through 1.61.0 and requires network access to a tracker endpoint that clients will connect to.

## Affected products

- anacrolix torrent through 1.61.0

## Timeline

- 2026-11-05: disclosed

## References

- [https://pkg.go.dev/](https://pkg.go.dev/)
- [https://github.com/anacrolix/torrent](https://github.com/anacrolix/torrent)

## Related threats

- [anacrolix torrent unbounded recursion in bencode decoder](https://junglewise.ai/threats/go-2026-6894-anacrolix-torrent-has-unbounded-recursion-in-the-bencode-590d3a6a)
- [anacrolix torrent unbounded recursion in bencode decoder](https://junglewise.ai/threats/anacrolix-torrent-has-unbounded-recursion-in-the-bencode-decoder-that-a1cc4a62)