libsignal-service-rs doesn't sanity check plaintext envelopes are not sanity-checked

published 2025-02-13 20 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-3985

cvss: 8.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits: 0; none known

libsignal-service-rs is a Rust version of the libsignal-service-java library which implements the core functionality to communicate with Signal servers. Prior to commit 82d70f6720e762898f34ae76b0894b0297d9b2f8, plaintext content envelopes could be injected by a server or a malicious client, and may have been able to bypass the end-to-end encryption and authentication. The vulnerability is fixed per 82d70f6720e762898f34ae76b0894b0297d9b2f8. The `Metadata` struct contains an additional `was_encrypted` field, which breaks the API, but should be easily resolvable. No known workarounds are available.

Patch / fix

links 1

github.com/whisperfish/libsignal-service-rs@82d70f6 commit

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 20 mo ago (2025-02-13)

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:N

Affected products

whisperfish libsignal-service-rs

Classification

Weakness

CWE-287 Improper Authentication
CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

Sources

CVE List CVE-2025-24904
NVD CVE-2025-24904

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary