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CVE-2025-9901

Libsoup: improper handling of http vary header in libsoup caching

5.9 Medium

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

0.47%Up 0.4 points since Sep 4, 2025
90%50%10%1%

What each source reports

CVE List Score used 5.9

Libsoup: improper handling of http vary header in libsoup caching

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.

Record
CVE-2025-9901
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-524
Updated
2026-11-05
EUVDEUVD-2025-26502 5.9

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.

Record
EUVD-2025-26502
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-05
GitHub AdvisoriesGHSA-hxjp-2xf5-wmrj 5.9

A flaw was found in libsoup’s caching mechanism, SoupCache, where the HTTP Vary header is ignored...

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.

Record
GHSA-hxjp-2xf5-wmrj
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-524
Updated
2026-11-02
NVD 5.9

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.

Record
CVE-2025-9901
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-524
Updated
2026-11-05
OSV 5.9

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.

Record
CVE-2025-9901
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2025-9901 5.9

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.

Record
DEBIAN-CVE-2025-9901
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVUBUNTU-CVE-2025-9901 5.9

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.

Record
UBUNTU-CVE-2025-9901
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-03
OSVAZL-67058 No score

CVE-2025-9901 affecting package libsoup 3.4.4-18

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.

Record
AZL-67058
Updated
2026-11-05
OSVAZL-67061 No score

CVE-2025-9901 affecting package libsoup 3.0.4-12

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.

Record
AZL-67061
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
libsoup
Azure Linux:3
through 3.4.4-18 None known
libsoup
Azure Linux:2
through 3.0.4-12 None known
libsoup
Debian:14
All versions, plus listed versions
2.1.2-12.1.5-12.1.7-12.2.100-12.2.101-1
Show 30 moreShow less
2.2.102-12.2.103-12.2.104-12.2.105-12.2.105-22.2.105-32.2.105-42.2.2-12.2.3-12.2.3-22.2.3-2sarge12.2.6-12.2.7-12.2.7-22.2.91-12.2.91-22.2.92-12.2.93-12.2.93-22.2.93-32.2.95.1-12.2.96-12.2.97-12.2.98-12.2.98-22.2.98-2+etch12.2.99-13.8.0-53.8.0-63.8.1-1
None known
libsoup2.4
Debian:12
All versions, plus listed versions
2.74.3-12.74.3-1+deb12u12.74.3-102.74.3-10.12.74.3-11
Show 11 moreShow less
2.74.3-22.74.3-32.74.3-3.1~exp12.74.3-3.1~exp22.74.3-3.1~exp32.74.3-52.74.3-62.74.3-72.74.3-82.74.3-8.12.74.3-9
None known
libsoup2.4
Debian:13
All versions, plus listed versions
2.74.3-10.12.74.3-11
None known
libsoup3
Debian:12
All versions, plus listed versions
3.2.2-23.2.3-0+deb12u13.2.3-0+deb12u23.3.1-13.4.0-1
Show 33 moreShow less
3.4.1-13.4.2-13.4.2-23.4.2-33.4.2-43.4.3-13.4.4-13.4.4-23.4.4-33.4.4-43.4.4-53.5.2-13.6.0-13.6.0-23.6.0-33.6.0-43.6.1-13.6.4-13.6.4-23.6.4-33.6.5-13.6.5-23.6.5-33.6.5-43.6.5-53.6.5-63.6.5-73.6.5-83.6.5-93.6.6-13.8.0-13.8.0-23.8.0-3
None known
libsoup3
Debian:13
All versions, plus listed versions
3.6.5-33.6.5-43.6.5-53.6.5-63.6.5-7
Show 6 moreShow less
3.6.5-83.6.5-93.6.6-13.8.0-13.8.0-23.8.0-3
None known
libsoup2.4
Ubuntu:Pro:16.04:LTS
All versions, plus listed versions
2.50.0-2debian12.52.1-12.52.2-12.52.2-1ubuntu0.12.52.2-1ubuntu0.2
Show 10 moreShow less
2.52.2-1ubuntu0.32.52.2-1ubuntu0.3+esm12.52.2-1ubuntu0.3+esm22.52.2-1ubuntu0.3+esm32.52.2-1ubuntu0.3+esm42.52.2-1ubuntu0.3+esm52.52.2-1ubuntu0.3+esm62.52.2-1ubuntu0.3+esm72.52.2-1ubuntu0.3+esm82.52.2-1ubuntu0.3+esm9
None known
libsoup2.4
Ubuntu:Pro:18.04:LTS
All versions, plus listed versions
2.60.1-12.60.2-12.60.2-22.60.3-12.61.90-1
Show 15 moreShow less
2.62.0-12.62.1-12.62.1-1ubuntu0.12.62.1-1ubuntu0.32.62.1-1ubuntu0.42.62.1-1ubuntu0.4+esm12.62.1-1ubuntu0.4+esm22.62.1-1ubuntu0.4+esm32.62.1-1ubuntu0.4+esm42.62.1-1ubuntu0.4+esm52.62.1-1ubuntu0.4+esm62.62.1-1ubuntu0.4+esm72.62.1-1ubuntu0.4+esm82.62.1-1ubuntu0.4+esm92.62.1-1ubuntu0.4+esm10
None known
libsoup2.4
Ubuntu:Pro:20.04:LTS
All versions, plus listed versions
2.68.2-0ubuntu12.68.2-12.68.2-22.68.2-2build22.69.90-1
Show 11 moreShow less
2.70.0-12.70.0-1ubuntu0.12.70.0-1ubuntu0.22.70.0-1ubuntu0.32.70.0-1ubuntu0.42.70.0-1ubuntu0.52.70.0-1ubuntu0.5+esm12.70.0-1ubuntu0.5+esm22.70.0-1ubuntu0.5+esm32.70.0-1ubuntu0.5+esm42.70.0-1ubuntu0.5+esm5
None known
Show 10 moreShow less
Affected packages
PackageAffectedFixed
libsoup2.4
Ubuntu:22.04:LTS
All versions, plus listed versions
2.72.0-3ubuntu32.74.1-12.74.2-22.74.2-32.74.2-3ubuntu0.1
Show 9 moreShow less
2.74.2-3ubuntu0.22.74.2-3ubuntu0.32.74.2-3ubuntu0.42.74.2-3ubuntu0.52.74.2-3ubuntu0.62.74.2-3ubuntu0.72.74.2-3ubuntu0.82.74.2-3ubuntu0.92.74.2-3ubuntu0.10
None known
libsoup3
Ubuntu:Pro:22.04:LTS
All versions, plus listed versions
3.0.4-23.0.4-33.0.5-13.0.7-0ubuntu13.0.7-0ubuntu1+esm1
Show 9 moreShow less
3.0.7-0ubuntu1+esm23.0.7-0ubuntu1+esm33.0.7-0ubuntu1+esm43.0.7-0ubuntu1+esm53.0.7-0ubuntu1+esm63.0.7-0ubuntu1+esm73.0.7-0ubuntu1+esm83.0.7-0ubuntu1+esm93.0.7-0ubuntu1+esm10
None known
libsoup2.4
Ubuntu:24.04:LTS
All versions, plus listed versions
2.74.3-12.74.3-22.74.3-32.74.3-62.74.3-6build1
Show 11 moreShow less
2.74.3-6ubuntu12.74.3-6ubuntu1.12.74.3-6ubuntu1.22.74.3-6ubuntu1.32.74.3-6ubuntu1.42.74.3-6ubuntu1.52.74.3-6ubuntu1.62.74.3-6ubuntu1.72.74.3-6ubuntu1.82.74.3-6ubuntu1.92.74.3-6ubuntu1.10
None known
libsoup3
Ubuntu:24.04:LTS
All versions, plus listed versions
3.4.2-43.4.4-13.4.4-23.4.4-43.4.4-5
Show 12 moreShow less
3.4.4-5build13.4.4-5build23.4.4-5ubuntu0.13.4.4-5ubuntu0.23.4.4-5ubuntu0.33.4.4-5ubuntu0.43.4.4-5ubuntu0.53.4.4-5ubuntu0.63.4.4-5ubuntu0.73.4.4-5ubuntu0.83.4.4-5ubuntu0.93.4.4-5ubuntu0.10
None known
libsoup2.4
Ubuntu:25.10
All versions, plus listed versions
2.74.3-102.74.3-10.12.74.3-10.1ubuntu12.74.3-10.1ubuntu22.74.3-10.1ubuntu32.74.3-10.1ubuntu42.74.3-10.1ubuntu4.1
None known
libsoup3
Ubuntu:25.10
All versions, plus listed versions
3.6.5-13.6.5-1ubuntu13.6.5-33.6.5-43.6.5-4ubuntu0.13.6.5-4ubuntu0.2
None known
libsoup2.4
Ubuntu:26.10
All versions, plus listed versions
2.74.3-10.1ubuntu5
None known
libsoup3
Ubuntu:26.10
All versions, plus listed versions
3.6.6-13.6.6-1ubuntu33.6.6-1ubuntu3.1
None known
libsoup3
Ubuntu:26.04:LTS
All versions, plus listed versions
3.6.5-43.6.5-53.6.5-63.6.5-73.6.5-93.6.6-13.6.6-1ubuntu0.13.6.6-1ubuntu0.2
None known
libsoup2.4
Ubuntu:Pro:26.04:LTS
All versions, plus listed versions
2.74.3-10.1ubuntu42.74.3-10.1ubuntu52.74.3-10.1ubuntu5+esm12.74.3-10.1ubuntu5+esm22.74.3-10.1ubuntu5+esm32.74.3-10.1ubuntu5+esm4
None known

History

History
RecordedChangedSources
affected, factsOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-9901 is a medium vulnerability (CVSS 5.9) in Red Hat Enterprise Linux 10, published September 3, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.47%, the 40th percentile. No source names a fixed version.

References

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