CVE-2025-26695

Email-address length disclosure via incorrect WKD padding

Published Mar 10, 2025 · Updated Apr 13, 2026

Information disclosure in Mozilla Thunderbird before 136 and ESR before 128.8 allows attackers to infer email-address length from WKD requests. Thunderbird applies an incorrect padding size to OpenPGP WKD key requests, leaving request length correlated with the requested address. Observation of the WKD network exchange is required; the disclosed value is the address length, not address contents or message data.

CVSS severity5.3
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Mozilla Thunderbird before 136 and ESR before 128.8 allows attackers to infer email-address length from WKD requests. Thunderbird applies an incorrect padding size to OpenPGP WKD key requests, leaving request length correlated with the requested address. Observation of the WKD network exchange is required; the disclosed value is the address length, not address contents or message data.

The record

CVE
CVE-2025-26695
Published
Mar 10, 2025
Updated
Apr 13, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1040
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 10, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1040Network Sniffing

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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