Description
The tor_realloc function in Tor before 0.2.1.29 and 0.2.2.x before 0.2.2.21-alpha does not validate a certain size value during memory allocation, which might allow remote attackers to cause a denial of service (daemon crash) via unspecified vectors, related to "underflow errors."
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | tor | 0.2.1.29-1 | — |
| Debian 13 | tor | 0.2.1.29-1 | — |
| Debian 12 | tor | 0.2.1.29-1 | — |
| Debian 5.0 | tor | 0.2.1.29-1~lenny+1 | DSA-2148-1 |
Advisories 1
- DSA-2148-1 tor - several Debian Security (DSA / DLA) · Mar 9, 2026
References
- [or-announce] 20110117 Tor 0.2.1.29 is released (security patches) mailing-list
- https://gitweb.torproject.org/tor.git/blob/refs/heads/release-0.2.2:/ChangeLog
- https://trac.torproject.org/projects/tor/ticket/2324
- http://blog.torproject.org/blog/tor-02129-released-security-patches
- tor-torrealloc-dos(64888) vdb-entry
- 45953 vdb-entry