Skip to content
Noroxi
NVD / CVE Program· CNA mozilla

CVE-2021-29957: If a MIME encoded email contains an OpenPGP inline signed or encrypted message part, but also contains an additional unprotected part…

MediumCVSS 4.3 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 17/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.94% (FIRST EPSS); higher than 61.3% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: thunderbird (Alpine:v3.16) 91.3.2-r0; thunderbird (Debian:10) 1:78.11.0-1~deb10u1; thunderbird (Debian:12) 1:78.10.2-1.
  • Mentioned 2 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to thunderbird (Alpine:v3.16) 91.3.2-r0; thunderbird (Debian:10) 1:78.11.0-1~deb10u1; thunderbird (Debian:12) 1:78.10.2-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

If a MIME encoded email contains an OpenPGP inline signed or encrypted message part, but also contains an additional unprotected part, Thunderbird did not indicate that only parts of the message are protected. This vulnerability affects Thunderbird < 78.10.2.

Published
Jun 24, 2021
Updated
Jun 16, 2026
EPSS
0.9% · 61th percentile
CWE
—

Report tools

JSON

Action score

17

Monitor

Low priority for now.

CVSS
17 / 40 · 4.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.9%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-29957

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits every 10 minutes on paid plans, on the hour on the free plan.

Your free account also gets you

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools, at most 30 a day (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for mozilla records
Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
mozillathunderbird

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • mozilla thunderbirdbefore 78.10.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (mozilla). Independent of NVD's CPE analysis and usually ahead of it.

  • Mozilla Thunderbird

    • unspecified and later · before 78.10.2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.16thunderbirdbefore 91.3.2-r091.3.2-r0
Debian:10thunderbirdbefore 1:78.11.0-1~deb10u11:78.11.0-1~deb10u1
Debian:12thunderbirdbefore 1:78.10.2-11:78.10.2-1
Debian:9thunderbirdbefore 1:78.11.0-1~deb9u11:78.11.0-1~deb9u1
openSUSE:Leap 15.3MozillaThunderbirdbefore 78.10.2-8.27.178.10.2-8.27.1
Red Hat:enterprise_linux:7::clientthunderbirdbefore 0:78.11.0-1.el7_90:78.11.0-1.el7_9
Red Hat:enterprise_linux:7::clientthunderbird-debuginfobefore 0:78.11.0-1.el7_90:78.11.0-1.el7_9
Red Hat:enterprise_linux:8::appstreamthunderbirdbefore 0:78.11.0-1.el8_40:78.11.0-1.el8_4
Red Hat:enterprise_linux:8::appstreamthunderbird-debuginfobefore 0:78.11.0-1.el8_40:78.11.0-1.el8_4
Red Hat:enterprise_linux:8::appstreamthunderbird-debugsourcebefore 0:78.11.0-1.el8_40:78.11.0-1.el8_4
Red Hat:rhel_eus:8.1::appstreamthunderbirdbefore 0:78.11.0-1.el8_10:78.11.0-1.el8_1
Red Hat:rhel_eus:8.1::appstreamthunderbird-debuginfobefore 0:78.11.0-1.el8_10:78.11.0-1.el8_1
Red Hat:rhel_eus:8.1::appstreamthunderbird-debugsourcebefore 0:78.11.0-1.el8_10:78.11.0-1.el8_1
Red Hat:rhel_eus:8.2::appstreamthunderbirdbefore 0:78.11.0-1.el8_20:78.11.0-1.el8_2
Red Hat:rhel_eus:8.2::appstreamthunderbird-debuginfobefore 0:78.11.0-1.el8_20:78.11.0-1.el8_2
Red Hat:rhel_eus:8.2::appstreamthunderbird-debugsourcebefore 0:78.11.0-1.el8_20:78.11.0-1.el8_2
Rocky Linux:8thunderbirdbefore 0:78.11.0-1.el8_40:78.11.0-1.el8_4
SUSE:Linux Enterprise Workstation Extension 15 SP2MozillaThunderbirdbefore 78.10.2-8.27.178.10.2-8.27.1

Same product

mozilla: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-11705A flaw in Thunderbird's implementation of iCal causes a stack buffer overflow in icalrecur_add_bydayrules when processing certain email…
    42Plan
  • CVE-2019-11704A flaw in Thunderbird's implementation of iCal causes a heap buffer overflow in icalmemory_strdup_and_dequote when processing certain email…
    42Plan
  • CVE-2019-11703A flaw in Thunderbird's implementation of iCal causes a heap buffer overflow in parser_get_next_char when processing certain email…
    42Plan

Published before and after this one in the same product

  • ← EarlierCVE-2021-29950Jun 24, 2021 · Thunderbird unprotects a secret OpenPGP key prior to using it for a decryption, signing or key import task.
    30Monitor
  • ← EarlierCVE-2021-29956Jun 24, 2021 · OpenPGP secret keys that were imported using Thunderbird version 78.8.1 up to version 78.10.1 were stored unencrypted on the user's local…
    17Monitor
  • Later →CVE-2021-29969Aug 5, 2021 · If Thunderbird was configured to use STARTTLS for an IMAP connection, and an attacker injected IMAP server responses prior to the…
    23Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:thunderbird91.3.2-r0 · Alpine:v3.16Package registry (OSV)
debian:thunderbird1:78.10.2-1 · Debian:12Package registry (OSV)
opensuse:MozillaThunderbird78.10.2-8.27.1 · openSUSE:Leap 15.3Package registry (OSV)
red hat:thunderbird0:78.11.0-1.el8_2 · Red Hat:rhel_eus:8.2::appstreamPackage registry (OSV)
red hat:thunderbird-debuginfo0:78.11.0-1.el8_2 · Red Hat:rhel_eus:8.2::appstreamPackage registry (OSV)
red hat:thunderbird-debugsource0:78.11.0-1.el8_2 · Red Hat:rhel_eus:8.2::appstreamPackage registry (OSV)
rocky linux:thunderbird0:78.11.0-1.el8_4 · Rocky Linux:8Package registry (OSV)
suse:MozillaThunderbird78.10.2-8.27.1 · SUSE:Linux Enterprise Workstation Extension 15 SP2Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
None
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records