CVE-2025-1936

Adding %00 and a fake extension to a jar: URL changed the interpretation of the contents

HIGH
7.3
CVSS Score
Published: March 4, 2025 at 01:31 PM UTC
Updated: October 5, 2026 at 03:10 PM UTC
2 products affected across 1 vendorFirefoxThunderbird

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Severity
HIGH7.3
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

jar: URLs retrieve local file content packaged in a ZIP archive. The null and everything after it was ignored when retrieving the content from the archive, but the fake extension after the null was used to determine the type of content. This could have been used to hide code in a web extension disguised as something else like an image. This vulnerability affects Firefox < 136, Firefox ESR < 128.8, Thunderbird < 136, and Thunderbird < 128.8.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 128.8.0v < 136.0
Vendor states this is fixed in 128.8 (unaffected)
Affected range stops below 128.8.0, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 136 (unaffected)
Affected range stops below 136.0, so it looks safe — our inference, not a vendor statement
v < 128.8.0129.0 ≤ v < 136.0
Vendor states this is fixed in 128.8 (unaffected)
Affected range stops below 128.8.0, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 136 (unaffected)
Affected range stops below 136.0, so it looks safe — our inference, not a vendor statement

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.3HIGHCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
LOW
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-158

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