LinOTP replay vulnerability with auto resynchronization enabled for TOTP token

Exploitation

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

CVSS 4.0

9.2 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2019-12887: 1.17% estimated exploitation activity in the next 30 days; percentile 67.54 (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.

LinOTP is prone to a replay attack with activated automatic resynchronization. This vulnerability may allow an attacker to successfully log in with OTP values recorded at a previous point in time. This attack is only possible if automatic resynchronization is enabled for the TOTP token type. The automatic resynchronization is deactivated by default. All other tokens are unaffected.

Published by the source

24 May 2022, 16:48 UTC

Last modified by the source

30 Sep 2024, 17:01 UTC

Source last checked

26 Oct 2026, 13:21 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-rqg8-xjp2-pg9w

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-rqg8-xjp2-pg9w

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# Patch Next advisory brief: CVE-2019-12887

Advisory: LinOTP replay vulnerability with auto resynchronization enabled for TOTP token
IDs: CVE-2019-12887, GHSA-rqg8-xjp2-pg9w
Record: https://patchnext.com/advisories/cve-2019-12887 (revision 3, source checked 26 Oct 2026, 13:21 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: linotp 2.11.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI linotp: affected < 2.11.1; fixed in 2.11.1

## Suggested inspection (read-only)
- `python -m pip show linotp`: 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 linotp.
- 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-rqg8-xjp2-pg9w (OSV record GHSA-rqg8-xjp2-pg9w lists affected ranges: PyPI linotp >=0 <2.11.1 (fixed))
- Verified: https://github.com/advisories/GHSA-rqg8-xjp2-pg9w (GitHub-reviewed advisory GHSA-rqg8-xjp2-pg9w lists affected ranges: PyPI linotp >=0 <2.11.1)

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