CVE-2026-57962: A malicious LDAP server, which a Thunderbird user is configured to query for address-book autocomplete, can st

Q: How do I fix CVE-2026-57962?

thunderbird: upgrade to 140.12.1, 152.0.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-57962 being exploited?

CVE-2026-57962 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-57962 affect?

CVE-2026-57962 affects thunderbird. Severity is medium (CVSS 5.3). A malicious LDAP server, which a Thunderbird user is configured to query for address-book autocomplete, can stash arbitrarily large amounts of attacker-supplied data into the Thunderbird LDAP client until it crashes due to memory exhaustion

Q: How urgent is CVE-2026-57962?

Priority 25/100. No elevated risk signals yet.

Routine

MEDIUM 5.3UPGRADE

CVE-2026-57962 is a medium-severity flaw (CVSS 5.3) affecting thunderbird. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A malicious LDAP server, which a Thunderbird user is configured to query for address-book autocomplete, can stash arbitrarily large amounts of attacker-supplied data into the Thunderbird LDAP client until it crashes due to memory exhaustion. This vulnerability was fixed in Thunderbird 152.0.1 and Thunderbird 140.12.1.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 73%)
CISA exploited list	No
Weakness	CWE-400
Published	2026-07-01
Last modified	2026-10-25

Publisher (CNA): Mozilla Corporation · Vendor: mozilla

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-01 02:17 UTCPublished CVE record published
2026-10-25 17:10 UTCUpdated Record last modified

mozilla thunderbird UPGRADE

Affected: < 140.12.1 · < 152.0.1

Fixed in: 140.12.1, 152.0.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy thunderbird || rpm -q thunderbird || thunderbird --version

2. UPGRADE to 140.12.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade thunderbird

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade thunderbird

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-57962?

thunderbird: upgrade to 140.12.1, 152.0.1. Exact commands for each OS are on this page.

Is CVE-2026-57962 being exploited?

CVE-2026-57962 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-57962 affect?

CVE-2026-57962 affects thunderbird. Severity is medium (CVSS 5.3). A malicious LDAP server, which a Thunderbird user is configured to query for address-book autocomplete, can stash arbitrarily large amounts of attacker-supplied data into the Thunderbird LDAP client until it crashes due to memory exhaustion

How urgent is CVE-2026-57962?

Priority 25/100. No elevated risk signals yet.

Software pages

Mozilla Thunderbird vulnerabilities

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References

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