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CVE-2020-12397· NVD / CVE Program· CNA mozilla

By encoding Unicode whitespace characters within the From email header, an attacker can spoof the sender email address that Thunderbird disp

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: 0.61% (FIRST EPSS).
  • 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 (Debian:10) 1:68.8.0-1~deb10u1; thunderbird (Debian:12) 1:68.8.0-1; thunderbird (Debian:8) 1:68.8.0-1~deb8u1.

Low priority for now. Upgrade to thunderbird (Debian:10) 1:68.8.0-1~deb10u1; thunderbird (Debian:12) 1:68.8.0-1; thunderbird (Debian:8) 1:68.8.0-1~deb8u1 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

By encoding Unicode whitespace characters within the From email header, an attacker can spoof the sender email address that Thunderbird displays. This vulnerability affects Thunderbird < 68.8.0.

MediumCVSS 4.3 · v3.1—No exploit Fix available
Published
May 22, 2020
Updated
Jun 16, 2026
EPSS
0.6% · 48th percentile

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 · 0.6%

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.

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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

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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.

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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
canonicalubuntu linux

Affected versions

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

  • canonical ubuntu linux16.04
  • canonical ubuntu linux18.04
  • canonical ubuntu linux19.10
  • canonical ubuntu linux20.04
  • mozilla thunderbirdbefore 68.8.0

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 68.8.0affected

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:10thunderbirdbefore 1:68.8.0-1~deb10u11:68.8.0-1~deb10u1
Debian:12thunderbirdbefore 1:68.8.0-11:68.8.0-1
Debian:8thunderbirdbefore 1:68.8.0-1~deb8u11:68.8.0-1~deb8u1
Debian:9thunderbirdbefore 1:68.8.0-1~deb9u11:68.8.0-1~deb9u1
openSUSE:Leap 15.1MozillaThunderbirdbefore 68.8.0-lp151.2.38.268.8.0-lp151.2.38.2
Red Hat:enterprise_linux:6::clientthunderbirdbefore 0:68.8.0-1.el6_100:68.8.0-1.el6_10
Red Hat:enterprise_linux:6::clientthunderbird-debuginfobefore 0:68.8.0-1.el6_100:68.8.0-1.el6_10
Red Hat:enterprise_linux:7::clientthunderbirdbefore 0:68.8.0-1.el7_80:68.8.0-1.el7_8
Red Hat:enterprise_linux:7::clientthunderbird-debuginfobefore 0:68.8.0-1.el7_80:68.8.0-1.el7_8
Red Hat:enterprise_linux:8::appstreamthunderbirdbefore 0:68.8.0-1.el8_20:68.8.0-1.el8_2
Red Hat:enterprise_linux:8::appstreamthunderbird-debuginfobefore 0:68.8.0-1.el8_20:68.8.0-1.el8_2
Red Hat:enterprise_linux:8::appstreamthunderbird-debugsourcebefore 0:68.8.0-1.el8_20:68.8.0-1.el8_2
Red Hat:rhel_e4s:8.0::appstreamthunderbirdbefore 0:68.8.0-1.el8_00:68.8.0-1.el8_0
Red Hat:rhel_e4s:8.0::appstreamthunderbird-debuginfobefore 0:68.8.0-1.el8_00:68.8.0-1.el8_0
Red Hat:rhel_e4s:8.0::appstreamthunderbird-debugsourcebefore 0:68.8.0-1.el8_00:68.8.0-1.el8_0
Red Hat:rhel_eus:8.1::appstreamthunderbirdbefore 0:68.8.0-1.el8_10:68.8.0-1.el8_1
Red Hat:rhel_eus:8.1::appstreamthunderbird-debuginfobefore 0:68.8.0-1.el8_10:68.8.0-1.el8_1
Red Hat:rhel_eus:8.1::appstreamthunderbird-debugsourcebefore 0:68.8.0-1.el8_10:68.8.0-1.el8_1
SUSE:Linux Enterprise Workstation Extension 15 SP1MozillaThunderbirdbefore 68.8.0-3.80.268.8.0-3.80.2

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 mess
    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 messages,
    42Plan

Published before and after this one in the same product

  • ← EarlierCVE-2020-6794Mar 2, 2020 · If a user saved passwords before Thunderbird 60 and then later set a master password, an unencrypted copy of these passwords is still access
    26Monitor
  • ← EarlierCVE-2020-6795Mar 2, 2020 · When processing a message that contains multiple S/MIME signatures, a bug in the MIME processing code caused a null pointer dereference, lea
    26Monitor
  • Later →CVE-2020-12398Jul 9, 2020 · If Thunderbird is configured to use STARTTLS for an IMAP server, and the server sends a PREAUTH response, then Thunderbird will continue wit
    30Monitor

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
debian:thunderbird1:68.8.0-1 · Debian:12Package registry (OSV)
opensuse:MozillaThunderbird68.8.0-lp151.2.38.2 · openSUSE:Leap 15.1Package registry (OSV)
red hat:thunderbird0:68.8.0-1.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:thunderbird-debuginfo0:68.8.0-1.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:thunderbird-debugsource0:68.8.0-1.el8_2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
suse:MozillaThunderbird68.8.0-3.80.2 · SUSE:Linux Enterprise Workstation Extension 15 SP1Package 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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).

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)

CWE-346 · Origin Validation Error

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.

Change log

  1. Fix✗ → ✓

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

References

Show all references (3 more)

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

All records