CVE-2023-0547: OCSP revocation status of recipient certificates was not checked when sending S/Mime encrypted email, and revo

Routine

MEDIUM 6.5UPGRADE

CVE-2023-0547 is a medium-severity flaw (CVSS 6.5) affecting thunderbird. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

OCSP revocation status of recipient certificates was not checked when sending S/Mime encrypted email, and revoked certificates would be accepted. Thunderbird versions from 68 to 102.9.1 were affected by this bug. This vulnerability affects Thunderbird < 102.10.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.4% (top 70%)
CISA exploited list	No
Weakness	CWE-295
Published	2023-06-02
Last modified	2026-10-23

Publisher (CNA): Mozilla Corporation · Vendor: mozilla

Last updated 2026-10-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-06-02 17:15 UTCPublished CVE record published
2026-10-23 23:10 UTCUpdated Record last modified

mozilla thunderbird UPGRADE

Affected: >= 68.0 and < 102.10

Fixed in: 102.10

Safe to downgrade to: a release before 68.0

1. Check installed version

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

2. UPGRADE to 102.10 (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.

3. If no update is available yet, DOWNGRADE to a release before 68.0 (Debian / Ubuntu)

apt-cache madison thunderbird sudo apt install thunderbird=<VERSION_BEFORE_68.0> sudo apt-mark hold thunderbird

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list thunderbird sudo dnf downgrade thunderbird-<VERSION_BEFORE_68.0> sudo dnf versionlock add thunderbird

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2023-0547?

thunderbird: upgrade to 102.10. Exact commands for each OS are on this page.

Is CVE-2023-0547 being exploited?

CVE-2023-0547 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-2023-0547 affect?

CVE-2023-0547 affects thunderbird. Severity is medium (CVSS 6.5). OCSP revocation status of recipient certificates was not checked when sending S/Mime encrypted email, and revoked certificates would be accepted. Thunderbird versions from 68 to 102.9.1 were affected by this bug. This vulnerability affects

How urgent is CVE-2023-0547?

Priority 30/100. No elevated risk signals yet.

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References

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