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Fencer Vulns
medium 6.3

CVE-2024-7531 json

Calling `PK11_Encrypt()` in NSS using CKM_CHACHA20 and the same buffer for input and output can result in plaintext on an Intel Sandy Bridg…

published 2024-08-06 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-48438

cvss
6.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

Calling `PK11_Encrypt()` in NSS using CKM_CHACHA20 and the same buffer for input and output can result in plaintext on an Intel Sandy Bridge processor. In Firefox this only affects the QUIC header protection feature when the connection is using the ChaCha20-Poly1305 cipher suite. The most likely outcome is connection failure, but if the connection persists despite the high packet loss it could be possible for a network observer to identify packets as coming from the same source despite a network path change. This vulnerability affects Firefox < 129, Firefox ESR < 115.14, and Firefox ESR < 128.1.

Patch / fix

  • Mozilla Firefox 129
  • Mozilla Firefox ESR 115.14, 128.1
  • nss Debian 14, Debian 13 2:3.103-1
  • firefox-esr Debian 12 115.14.0esr-1~deb12u1
  • firefox-esr Debian 14, Debian 13 115.14.0esr-1

debian advisories DEBIAN-CVE-2024-7531

  • firefox Ubuntu 20.04 LTS 129.0.1+build1-0ubuntu0.20.04.1

ubuntu advisories UBUNTU-CVE-2024-7531

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • MozillaFirefox SLES for SAP 15 SP4, SLES for SAP 15 SP3, SLES for SAP 15 SP2 +12 more 128.1.0-150200.152.146.1
  • MozillaFirefox-branding-SLE SLES for SAP 15 SP4, SLES for SAP 15 SP3, SLES for SAP 15 SP2 +12 more 128-150200.9.16.1
  • MozillaFirefox SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 128.1.0-112.221.1
  • MozillaFirefox-branding-SLE SLES for SAP 12 SP5, SLES 12 SP5 128-35.15.1

suse advisories SUSE-SU-2024:3003-1SUSE-SU-2024:2876-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 129.0-1.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:14260-1

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-2024-7531 updated cvss 3.1

mozilla: nss: PK11_Encrypt using CKM_CHACHA20 can reveal plaintext on Intel Sandy Bridge machines

  • Red Hat Enterprise Linux 6 nss, firefox, nss-tools, nss-sysinit Red Hat Enterprise Linux 7 nss, firefox, nss-tools, nss-sysinit
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 nss, nss-util, nss-tools, nss-softokn, nss-sysinit, nss-softokn-freebl Red Hat Enterprise Linux 9 nss, nspr, nss-util, nss-tools, nss-softokn, nss-sysinit, +1 more
    affected: no fix available
  • Red Hat Enterprise Linux AppStream AUS (v. 8.2) firefox 128.2.0-1.el8_2
    fixed: vendor fix RHSA-2024:6839
  • Red Hat Enterprise Linux 6 thunderbird Red Hat Enterprise Linux 7 thunderbird Red Hat Enterprise Linux 8 firefox, thunderbird Red Hat Enterprise Linux 9 firefox, firefox-x11, thunderbird
    not affected: vulnerable code not present

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
2 y ago

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CNA 3.1 6.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

Affected products

  • Mozilla Firefox
  • Mozilla Firefox ESR

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

References

Sources

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.