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Full vulnerability report · 2023
CVE-2023-29539High confidence

This could have led to reflected file download attacks potentially tricking users to install malware

Mozilla · Firefox

8.8HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.74% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Mozilla Firefox and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Distribution package intelligence

Release-specific package status

Alpine, Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

12 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Alpine v3.23v3.23 · communityfirefox-esrVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.102.10.0-r0Alpine Security Database ↗Source updated 11 Sep 2026
Alpine v3.22v3.22 · communityfirefox-esrVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.102.10.0-r0Alpine Security Database ↗Source updated 11 Sep 2026
Alpine v3.21v3.21 · communityfirefox-esrVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.102.10.0-r0Alpine Security Database ↗Source updated 19 Aug 2026
Debian trixietrixie · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.102.10.0esr-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian trixietrixie · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:102.10.0-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.102.10.0esr-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:102.10.0-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.102.10.0esr-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:102.10.0-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourcefirefoxVendor fix publishedDebian records a fixed source-package version for this release.112.0-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.102.10.0esr-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:102.10.0-1Debian Security Tracker ↗Source updated 5 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2023-29539 · CSAF 2.0 · revision 3 · finalRed Hat Product SecurityMozilla: Content-Disposition filename truncation leads to Reflected File Download
4 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • firefox as a component of Red Hat Enterprise Linux 6
  • firefox.src as a component of Red Hat Enterprise Linux 6
  • thunderbird as a component of Red Hat Enterprise Linux 6
  • thunderbird.src as a component of Red Hat Enterprise Linux 6
Summary
The Mozilla Foundation Security Advisory describes this flaw as: When handling the filename directive in the Content-Disposition header, the filename would be truncated if the filename contained a NULL character. This could have led to reflected file download attacks potentially tricking users to install malware.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing the update, Firefox must be restarted for the changes to take effect.
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2023-33081

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

When handling the filename directive in the Content-Disposition header, the filename would be truncated if the filename contained a NULL character. This could have led to reflected file download attacks potentially tricking users to install malware. This vulnerability affects Firefox < 112, Focus for Android < 112, Firefox ESR < 102.10, Firefox for Android < 112, and Thunderbird < 102.10.

What

When handling the filename directive in the Content-Disposition header, the filename would be truncated if the filename contained a NULL character. This could have led to reflected file download attacks potentially tricking users to install malware. This vulnerability affects Firefox < 112, Focus for Android < 112, Firefox ESR < 102.10, Firefox for Android < 112, and Thunderbird < 102.10.

Why

The product dereferences a pointer that it expects to be valid but is NULL.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

When handling the filename directive in the Content-Disposition header, the filename would be truncated if the filename contained a NULL character. This could have led to reflected file download attacks potentially tricking users to install malware. This vulnerability affects Firefox < 112, Focus for Android < 112, Firefox ESR < 102.10, Firefox for Android < 112, and Thunderbird < 102.10.

Why

The product dereferences a pointer that it expects to be valid but is NULL.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → NULL Pointer Dereference → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-476 ↗

CWE-476: NULL Pointer Dereference. The product dereferences a pointer that it expects to be valid but is NULL.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-476
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2023-2031Xerox FreeFlow Print Server: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Xerox FreeFlow Print Server ausnutzen, um die Vertraulichkeit, Verfügbarkeit und Integrität des Systems zu gefährden.

Official advisory ↗
BSI · German · WID-SEC-2023-0941Mozilla Firefox und Thunderbird: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Mozilla Firefox, Mozilla Firefox ESR und Mozilla Thunderbird ausnutzen, um beliebigen Code auszuführen, um Informationen offenzulegen und um Sicherheitsmechanismen zu umgehen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20230607Security Bulletin 07 Jun 2023

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 07 Jun 2023, published on 7 June 2023. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2023-AVI-0303Multiples vulnérabilités dans les produits Mozilla

d?id=CVE-2023-29479 Référence CVE CVE-2023-29531 https://www.cve.org/CVERecord?id=CVE-2023-29531 Référence CVE CVE-2023-29532 https://www.cve.org/CVERecord?id=CVE-2023-29532 Référence CVE CVE-2023-29533 https://www.cve.org/CVERecord?id=CVE-2023-29533 Référence CVE CVE-2023-29534 https://www.cve.org/CVERecord?id=CVE-2023-29534 Référence CVE CVE-2023-29535 https://www.cve.org/CVERecord?id=CVE-2023-29535 Référence CVE CVE-2023-29536 https://www.cve.org/CVERecord?id=CVE-2023-29536 Référence CVE CVE-2023-29537 https://www.cve.org/CVERecord?id=CVE-2023-29537 Référence CVE CVE-2023-29538 https://www.cve.org/CVERecord?id=CVE-2023-29538 Référence CVE CVE-2023-29539 https://www.cve.org/CVERecord?id=CVE-2023-29539 Référence CVE CVE-2023-29540 https://www.cve.org/CVERecord?id=CVE-2023-29540 Référence CVE CVE-2023-29541 https://www.cve.org/CVERecord?id=CVE-2023-29541 Référence CVE CVE-2023-29542 https://www.cve.org/CVERecord?id=CVE-2023-29542 Référence CVE CVE-2023-29543 https://www.cve.org/CVERecord?id=CVE-2023-29543 Référence CVE CVE-2023-29544 https://www.cve.org/CVERecord?id=CVE-2023-29544 Référence CVE CVE-2023-29545 https://www.cve.org/CVERecord?id=CVE-2023-29545 Référence CVE CVE-2023-29546 https://www.cve.org/CVERecord?id=CVE-2023-29546 Référence CVE CVE-2023-29547 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2023-022557複数の Mozilla Foundation 製品における NULL ポインタデリファレンスに関する脆弱性

Mozilla Firefox、Mozilla Firefox ESR、Mozilla Focus 等複数の Mozilla Foundation 製品には、NULL ポインタデリファレンスに関する脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5909Mozilla 제품 보안 업데이트 권고

p에서 발생하는 Double-free 취약점 (CVE-2023-1999) [2] [3] [4] o Firefox, Firefox ESR, Thunderbird에서 Garbage Collector 압축 후 메모리 손상 가능 취약점 (CVE-2023-29535) [2] [3] [4] o Firefox, Firefox ESR, Thunderbird에서 유효하지 않은 JavaScript 코드로 인해 발생하는 메모리 손상 취약점 (CVE-2023-29536) [2] [3] [4] o Firefox에서 글꼴 초기화 코드의 데이터 경합(Data Race)으로 발생하는 메모리 손상 취약점 (CVE-2023-29537) [2] o Firefox에서 WebExtensions으로 인해 디렉터리 정보 유출 가능 취약점 (CVE-2023-29538) [2] o Thunderbird에서 S/Mime 수신자 인증서의 폐기 상태 확인되지 않는 취약점 (CVE-2023-0547) [4] o Thunderbird에서 특정 OpenPGP 메시지 처리 시 중단 취약점 (CVE-2023-29479) [4] o Firefox, Firefox ESR, Thunderbird에서 Content-Disposition 파일 이름 잘림으로 인해 발생하는 Reflected 파일 다운로드 취약점 (CVE-2023-29539) [2] [3] [4] o Firefox에서 sourceMappingUrls의 리다이렉트 시 발생하는 Iframe 샌드박스 우회 취약점 (CVE-2023-29540) [2] o Linux 용 Firefox, Firefox ESR, Thunderbird에서 악의적인 확장자 파일 다운로드 취약점 (CVE-2023-29541) [2] [3] [4] o Firefox, Firefox ESR, Thunderbird에서 파일 다운로드 확장자 제한 우회 취약점 (CVE-2023-29542) [2] [3] [4] o Firefox의 디버깅 API에서 발생하는 Use-after-free 취약점 (CVE-2023-29543) [2] o Firefox에서 발생하는 Garbage Collector의 메모리 손상 취약점 (CVE-2023-29544) [2] o Windows 용 Firefox, Firefox ESR, Thunderbird에서 다른 이름으로 링크 저장 시 발생하는 환경 변수 취약점 (CVE-2023-29545) [2] [3] [4] o Android 용 Firefox에서 발생하는 Private Browsing의 주소 표시줄 화면 녹화 취약점 (CVE-2023-29546) [2] o Firefox에서 발생하는 보안 문서 쿠키 스푸핑 취약점 (CVE-202

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
Action
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing the update, Firefox must be restarted for the changes to take effect.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 2 Jun 2023 · Last source change 9 Jan 2025, 15:44 UTC · CWE-476 · NULL Pointer Dereference

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2023-33081
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceNIST NVD
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    unspecified < 112; unspecified < 102.10 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    unspecified < 112; unspecified < 102.10 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing the update, Firefox must be restarted for the changes to take effect.
    Red Hat Product Security ↗
  2. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    Red Hat Product Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2023-33081↗Red Hat Product Security security advisory↗CVE authority or vendor reference↗Vendor advisory↗Vendor advisory↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2023-29539 · cve.blacktree.nl