Cyber Resilience

CVE-2022-26485

Memory Safety in Mozilla Firefox ≤ 91.6.1

CISA KEVActive ExploitationEUVD ExploitedPublic PoCMemory Safety
Published
22 December 2022
Modified
04 November 2025
KEV Added
07 March 2022
Patch / advisory
View advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS Score 0.14 96th percentile
Risk Priority 90 floored blend · peak EPSS

Summary

CVE-2022-26485 is a high-severity Use After Free (CWE-416) vulnerability in Mozilla Firefox. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked in the top 4% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2022-26485 is a use-after-free vulnerability (CWE-416) that arises when an XSLT parameter is removed during processing. It affects Firefox versions prior to 97.0.2, Firefox ESR prior to 91.6.1, Firefox for Android prior to 97.3.0, Thunderbird prior to 91.6.2, and Focus prior to 97.3.0. The flaw received a CVSS 3.1 score of 8.8.

An attacker can exploit the issue by serving malicious content that triggers the use-after-free condition, leading to arbitrary code execution with the privileges of the affected application. Exploitation requires user interaction such as visiting a crafted web page or opening a malicious email attachment, and in-the-wild attacks abusing the flaw have been reported.

Mozilla security advisories MFSA2022-09 recommend upgrading to the fixed versions listed above. The vulnerability also appears in the CISA Known Exploited Vulnerabilities catalog, confirming that federal agencies must apply the patches.

EPSS for the CVE rose from a low baseline after disclosure to a peak of 0.1738 on 2023-02-01 before receding to the current value of 0.0285, indicating a period of increased exploitation interest following public release.

EU & UK References

Vulnerability Data

Removing an XSLT parameter during processing could have lead to an exploitable use-after-free. We have had reports of attacks in the wild abusing this flaw. This vulnerability affects Firefox < 97.0.2, Firefox ESR < 91.6.1, Firefox for Android < 97.3.0,…

more

Thunderbird < 91.6.2, and Focus < 97.3.0.

CWE(s)
CWE-416
KEV Date Added
07 March 2022

Related Threats

MITRE ATT&CK Enterprise Techniques

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2022-26486Same product: Mozilla Firefoxboth on KEV
CVE-2020-6819Same product: Mozilla Firefoxboth on KEV
CVE-2026-2765Same product: Mozilla Firefox
CVE-2026-2767Same product: Mozilla Firefox
CVE-2026-2770Same product: Mozilla Firefox
CVE-2024-5702Same product: Mozilla Firefox
CVE-2024-4770Same product: Mozilla Firefox
CVE-2026-0884Same product: Mozilla Firefox
CVE-2025-1930Same product: Mozilla Firefox
CVE-2026-2799Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 91.6.1 · ≤ 97.0.2 · ≤ 97.3.0
mozilla
firefox focus
≤ 97.3.0
mozilla
thunderbird
≤ 91.6.2

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 3 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V1.4.3

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-16 Memory Protection
addresses: CWE-416

Use-after-free exploits that achieve arbitrary code execution are blocked or significantly hardened by non-executable pages and ASLR.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly incorporate memory-safety tooling and reviews that prevent most use-after-free defects.

ID.RA-01 partial match
prevents

Vulnerability identification processes can discover use-after-free issues via scanning or analysis but do not prevent their introduction.

PR.PS-02 partial match
prevents

Routine patching removes known use-after-free instances after they have been introduced in released software.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect use-after-free bugs before release.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates memory-safety practices that reduce use-after-free defects.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify memory-management rules that mitigate use-after-free.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles include memory-safety design choices that limit use-after-free exposure.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly prescribe avoidance of use-after-free patterns.

A.8.32 Change management partial match
prevents

Change-management processes help ensure memory-safety fixes are deployed consistently.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248592 OL 8 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416
RHEL 8 (1 rule)
  • V-230279 RHEL 8 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416
RHEL 9 (1 rule)
  • V-257794 RHEL 9 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416

References