transport/fc.rs: panic attempting to send MAX_DATA with value larger max varint

published 2025-06-26 16 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-28762

cvss: 6.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 16%
public exploits: 0; none known

Improper Input Validation vulnerability in Mozilla neqo leads to an unexploitable crash..This issue affects neqo: from 0.4.24 through 0.13.2.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-6703 updated 2026-11-06 cvss 3.5

neqo-transport: neqo-transport panic

Red Hat Enterprise Linux 7 firefox Red Hat Enterprise Linux 8 firefox, thunderbird Red Hat Enterprise Linux 9 gjs, polkit, firefox, firefox-x11, polkit-libs, thunderbird Red Hat Enterprise Linux 10 gjs, firefox, thunderbird
affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 16 mo ago (2025-06-26)

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	2.3	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/AU:Y/R:A/RE:L/U:Clear
CNA	4.0	2.3	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:A/V:X/RE:L/U:Clear
NVD	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected products

Mozilla neqo

Classification

Weakness

CWE-20 Improper Input Validation

References

github.com /mozilla/neqo/security/advisories/GHSA-jfv6-x22w-grhf
vendor-advisory

Sources

CVE List CVE-2025-6703
NVD CVE-2025-6703

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