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Full vulnerability report · 2021
CVE-2021-42096High confidence

GNU Mailman before 2.1.35 may allow remote Privilege Escalation

Unknown · Unknown

4.3MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 1.25% 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 Unknown Unknown 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: As exposure requiresRemediation target: Within 365 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.

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-2021-42096 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitymailman: CSRF token derived from admin password allows offline brute-force attack
52 fixed

The vendor explicitly identifies these products or versions as containing the fix.

  • mailman-3:2.1.29-4.module+el8.1.0+13242+45286865.1.aarch64 (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
  • mailman-3:2.1.29-4.module+el8.1.0+13242+45286865.1.ppc64le (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
  • mailman-3:2.1.29-4.module+el8.1.0+13242+45286865.1.s390x (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
  • mailman-3:2.1.29-4.module+el8.1.0+13242+45286865.1.src (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
  • mailman-3:2.1.29-4.module+el8.1.0+13242+45286865.1.x86_64 (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
  • mailman-debuginfo-3:2.1.29-4.module+el8.1.0+13242+45286865.1.aarch64 (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
  • mailman-debuginfo-3:2.1.29-4.module+el8.1.0+13242+45286865.1.ppc64le (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
  • mailman-debuginfo-3:2.1.29-4.module+el8.1.0+13242+45286865.1.s390x (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
  • mailman-debuginfo-3:2.1.29-4.module+el8.1.0+13242+45286865.1.x86_64 (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
  • mailman-debugsource-3:2.1.29-4.module+el8.1.0+13242+45286865.1.aarch64 (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
  • mailman-debugsource-3:2.1.29-4.module+el8.1.0+13242+45286865.1.ppc64le (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
  • mailman-debugsource-3:2.1.29-4.module+el8.1.0+13242+45286865.1.s390x (mailman:2.1) as a component of Red Hat Enterprise Linux AppStream EUS (v. 8.1)
Summary
Sensitive information is exposed to unprivileged users in mailman. The hash of the list admin password is used to derive the CSRF (Cross-site Request Forgery) token, which is exposed to unprivileged members of a list. Malicious members may use the CSRF token to perform an offline brute-force attack to retrieve the list admin password.
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
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-2021-29082

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 actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
01

What, why and how

GNU Mailman before 2.1.35 may allow remote Privilege Escalation. A certain csrf_token value is derived from the admin password, and may be useful in conducting a brute-force attack against that password.

What

GNU Mailman before 2.1.35 may allow remote Privilege Escalation. A certain csrf_token value is derived from the admin password, and may be useful in conducting a brute-force attack against that password.

Why

The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may gain additional privileges.

What

GNU Mailman before 2.1.35 may allow remote Privilege Escalation. A certain csrf_token value is derived from the admin password, and may be useful in conducting a brute-force attack against that password.

Why

The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may gain additional privileges.

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 → Improper Restriction of Excessive Authentication Attempts → gain additional privileges
Attack surface
Network
Privileges required
Low: a basic authenticated account is required
User interaction
None
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-307 ↗

CWE-307: Improper Restriction of Excessive Authentication Attempts. The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.

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:L/UI:N/S:U/C:L/I:N/A:N

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.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CLowConfidentiality impact: A successful attack can cause a limited loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
NetworkPrivilege escalationCWE-307
A

Official authority intelligence

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

Cyber Security Agency of Singapore · English · CSA-SB-20211027Security Bulletin 27 Oct 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 27 Oct 2021, published on 27 October 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-014102GNU Mailman における過度な認証試行の不適切な制限に関する脆弱性

GNU Mailman には、過度な認証試行の不適切な制限に関する脆弱性が存在します。

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
n/a
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
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 21 Oct 2021 · Last source change 4 Aug 2024, 03:22 UTC · CWE-307 · Improper Restriction of Excessive Authentication Attempts

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-2021-29082
Product sourceUnavailable
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceNIST NVD
NVD statusNVD modified after enrichment

Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    n/a · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    n/a · 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
    Red Hat Product Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2021-29082↗Red Hat Product Security security advisory↗Patch or update reference↗Patch or update reference↗CVE authority or vendor reference↗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-2021-42096 · cve.blacktree.nl