CyberSecBulletin
CVE-2026-13707NVD status: Analyzed

OAuth: Session Fixation

Published Updated By the CyberSecBulletin desk

CVE-2026-13707 is a high-severity session fixation vulnerability in OAuth from Wikimedia Foundation, with a CVSS 3.1 base score of 7.6 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, but only if a user takes part, for example by opening a link or file. Affected OAuth versions: 1.46.0, 1.45.4, 1.44.6, 1.43.9 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.34% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Mediawiki to 1.43.9 or 1.44.6 or 1.45.4, whichever matches your release line, or a later version.
  2. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
Wikimedia FoundationOAuth1.46.0, 1.45.4, 1.44.6, 1.43.9 and earlierNot stated
MediaWikiMediawiki1.43.0 up to, but not including, 1.43.9; 1.44.0 up to, but not including, 1.44.6; 1.45.0 up to, but not including, 1.45.4; 1.46.01.43.9, 1.44.6, 1.45.4

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
LowPerformance or availability is reduced.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:L. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 4.00.0NoneCNA
CVSS 3.17.6HighNVD

Official description

Session fixation vulnerability in Wikimedia Foundation OAuth. This vulnerability is associated with program files src/Backend/MWOAuthServer.Php. This issue affects OAuth: from * through 1.46.0, 1.45.4, 1.44.6, 1.43.9.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Session Fixation

Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.

How developers prevent this class of flaw

  • Invalidate any existing session identifiers prior to authorizing a new user session.
  • For platforms such as ASP that do not generate new values for sessionid cookies, utilize a secondary cookie. In this approach, set a secondary cookie on the user's browser to a random value and set a session variable to the same value. If the session variable and the cookie value ever don't match, invalidate the session, and force the user to log on again.
  • Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.

More Session Fixation vulnerabilities (CWE-384)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other references

Recent Session Fixation vulnerabilities

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