What is CVE-2024-1551?

CVE-2024-1551 is a medium-severity vulnerability in Mozilla Firefox, classified under Reliance on Cookies without Validation and Integrity Checking. CVSS score: 6.1/10. Published 2024-02-20.

How severe is CVE-2024-1551?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Is CVE-2024-1551 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Mozilla Firefox

CVE-2024-1551

Set-Cookie response headers were being incorrectly honored in multipart HTTP responses. If an attacker could control the Content-Type response header, as well as control part of the response body, they could inject Set-Cookie response headers that would have been honored by the browser. This vulnerability affects Firefox < 123, Firefox ESR < 115.8, and Thunderbird < 115.8.

Published 2024-02-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.007 (53.1th percentile), scored 2026-10-03.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 53.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Mozilla Firefox — versions unspecified
Mozilla Firefox Esr — versions unspecified
Mozilla Thunderbird — versions unspecified
Debian Linux — versions 10.0

Weakness classification (CWE)

CWE-565 — Reliance on Cookies without Validation and Integrity Checking

Public proof-of-concept exploits

fkie-cad/nvd-json-data-feeds

References

bugzilla.mozilla.org/show_bug.cgi (Exploit, Issue Tracking)
www.mozilla.org/security/advisories/mfsa2024-05/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2024-06/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2024-07/ (Vendor Advisory)
lists.debian.org/debian-lts-announce/2024/03/msg00000.html (Third Party Advisory)
lists.debian.org/debian-lts-announce/2024/03/msg00001.html (Third Party Advisory)

Frequently asked questions

What is CVE-2024-1551?: CVE-2024-1551 is a medium-severity vulnerability in Mozilla Firefox, classified under Reliance on Cookies without Validation and Integrity Checking. CVSS score: 6.1/10. Published 2024-02-20.
How severe is CVE-2024-1551?: Medium severity. CVSS v3 base score is 6.1 out of 10.
Is CVE-2024-1551 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.