5.9

CVE-2025-9901: libsoup2.4

CVSS: 5.9v3.1MediumDeferred
AliasesUBUNTU-CVE-2025-9901DEBIAN-CVE-2025-9901
Published 03-09-2025Last modified 30-06-2026
Open JSON

Vulnerability summary

CVE-2025-9901 is a medium (CVSS 5.9) vulnerability in libsoup2.4. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 38% of scored vulnerabilities.

Overall risk
24/100
0100
Low · default modelHow is this calculated?
CVSS score
5.9/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.45%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 03-09-2025
    PublishedVulnerability first disclosed.
  2. 30-06-2026
    Last modifiedVulnerability information updated.

Description

A flaw was found in libsoup’s caching mechanism, SoupCache, where the HTTP Vary header is ignored when evaluating cached responses. This header ensures that responses vary appropriately based on request headers such as language or authentication. Without this check, cached content can be incorrectly reused across different requests, potentially exposing sensitive user information. While the issue is unlikely to affect everyday desktop use, it could result in confidentiality breaches in proxy or multi-user environments.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.45%

Chance of exploitation in the next 30 days

Percentile

38%

Versus all other CVEs

30-day change

0.00 pp

From 0.46% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.45%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Debian2 products
  • libsoup2.4All versions (No fix recorded)
  • libsoup3All versions (No fix recorded)
Ubuntu2 products
  • libsoup2.4All versions (No fix recorded)
  • libsoup3All versions (No fix recorded)

2 vendors · 4 products

References

6 links