# CVE-2026-77639: tor: Tor before 0.4.9.9 was prone to a compression bomb bypass where an attacker could concatenate many gzip or zlib sub-s...

CVE-2026-77639 is fixed in tor on 1 platform, first by DEBIAN-CVE-2026-77639, released August 21, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-77639
- Priority: Routine
- CVSS: 5.3 (medium)
- EPSS: 0.0039
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 20, 2026

## Description

Tor before 0.4.9.9 was prone to a compression bomb bypass where an attacker could concatenate many gzip or zlib sub-streams, each just under the per-stream detection threshold, to avoid the compression bomb check entirely. This is TROVE-2026-022.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | tor Debian 12.15 (bookworm) | 0.4.9.9-1 | [DEBIAN-CVE-2026-77639](https://patchblox.com/security/data/fix/linux/debian-cve-2026-77639.md) | Aug 21, 2026 |
| Linux | tor Debian 13.5 (trixie) | 0.4.9.11-0+deb13u1 | [DEBIAN-CVE-2026-77639](https://patchblox.com/security/data/fix/linux/debian-cve-2026-77639.md) | Aug 21, 2026 |
| Linux | tor Debian 14 | 0.4.9.9-1 | [DEBIAN-CVE-2026-77639](https://patchblox.com/security/data/fix/linux/debian-cve-2026-77639.md) | Aug 21, 2026 |

---

Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.