TorBot vulnerable to Inefficient Regular Expression Complexity in validate_link

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.6 · CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2023-45813: 0.96% estimated exploitation activity in the next 30 days; percentile 61.59 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The torbot.modules.validators.validatelink function uses the python-validators URL validation regex. This particular regular expression has an exponential complexity which allows an attacker to cause an application crash using a well-crafted argument.. Details https://github.com/DedSecInside/TorBot/blob/d2b89192379ad033ffc7044efff26e16ccc02d5a/torbot/modules/validators.py#L13 An attacker can use a well-crafted URL argument to exploit the vulnerability in the regular expression and cause a Denial of Service on the system. PoC I have uploaded a secret gist containing a PoC (https://gist.github.com/ikkebr/6041055314f1cfb8e65b2a1acbaae12c). By adding one special character at the end of the user argument of the URL, the regular expression will take exponentially longer to compute. For a string of size 10k, the regex will take 0.01s without the well-crafted URL and 1.3s with the well-crafted URL exploit. For a string of size 50k, the regex will take 0.03s without the well-crafted…

Published by the source

19 Oct 2023, 12:33 UTC

Last modified by the source

10 Sep 2026, 03:49 UTC

Source last checked

26 Oct 2026, 13:12 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-72qw-p7hh-m3ff

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-72qw-p7hh-m3ff

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# Patch Next advisory brief: CVE-2023-45813

Advisory: TorBot vulnerable to Inefficient Regular Expression Complexity in validate_link
IDs: CVE-2023-45813, GHSA-72qw-p7hh-m3ff
Record: https://patchnext.com/advisories/cve-2023-45813 (revision 2, source checked 26 Oct 2026, 13:12 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: torbot 4.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI torbot: affected < 4.0.0; fixed in 4.0.0

## Suggested inspection (read-only)
- `python -m pip show torbot`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on torbot.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-72qw-p7hh-m3ff (OSV record GHSA-72qw-p7hh-m3ff lists affected ranges: PyPI torbot >=0 <4.0.0 (fixed))
- Verified: https://github.com/advisories/GHSA-72qw-p7hh-m3ff (GitHub-reviewed advisory GHSA-72qw-p7hh-m3ff lists affected ranges: PyPI torbot >=0 <4.0.0)

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