CVE-2026-14899
Off-by-one out of bounds read in MIME header parser for forwarding
CVE-2026-14899 is fixed in 134 products on 2 platforms, first by Mozilla Thunderbird (af) 141.0, released July 22, 2025. It is not reported as exploited. Patch Radar priority: High.
HighFixed on 2 platforms
CVSS
8.8
moderate
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0047
40th percentile
The code to parse MIME headers for display when forwarding a message (if the setting to view all headers was enabled) had an off-by-one error, allowing a single byte to be read from the memory after the buffer for the headers, and potentially crashing Thunderbird. This vulnerability was fixed in Thunderbird 153 and Thunderbird 140.13.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Windows apps | |||
| Mozilla Thunderbird (af) | 141.0 | Mozilla Thunderbird (af) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (ar) | 141.0 | Mozilla Thunderbird (ar) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (ast) | 141.0 | Mozilla Thunderbird (ast) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (be) | 141.0 | Mozilla Thunderbird (be) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (bg) | 141.0 | Mozilla Thunderbird (bg) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (br) | 141.0 | Mozilla Thunderbird (br) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (ca) | 141.0 | Mozilla Thunderbird (ca) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (cak) | 141.0 | Mozilla Thunderbird (cak) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (cs) | 141.0 | Mozilla Thunderbird (cs) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (cy) | 141.0 | Mozilla Thunderbird (cy) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (da) | 141.0 | Mozilla Thunderbird (da) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (de) | 141.0 | Mozilla Thunderbird (de) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (dsb) | 141.0 | Mozilla Thunderbird (dsb) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (el) | 141.0 | Mozilla Thunderbird (el) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (en-CA) | 141.0 | Mozilla Thunderbird (en-CA) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (en-GB) | 141.0 | Mozilla Thunderbird (en-GB) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (en-US) | 141.0 | Mozilla Thunderbird (en-US) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (es-AR) | 141.0 | Mozilla Thunderbird (es-AR) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (es-ES) | 141.0 | Mozilla Thunderbird (es-ES) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (es-MX) | 141.0 | Mozilla Thunderbird (es-MX) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (et) | 141.0 | Mozilla Thunderbird (et) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (eu) | 141.0 | Mozilla Thunderbird (eu) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (fi) | 141.0 | Mozilla Thunderbird (fi) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (fr) | 141.0 | Mozilla Thunderbird (fr) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (fy-NL) | 141.0 | Mozilla Thunderbird (fy-NL) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (ga-IE) | 141.0 | Mozilla Thunderbird (ga-IE) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (gd) | 141.0 | Mozilla Thunderbird (gd) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (gl) | 141.0 | Mozilla Thunderbird (gl) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (he) | 141.0 | Mozilla Thunderbird (he) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (hr) | 141.0 | Mozilla Thunderbird (hr) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (hsb) | 141.0 | Mozilla Thunderbird (hsb) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (hu) | 141.0 | Mozilla Thunderbird (hu) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (hy-AM) | 141.0 | Mozilla Thunderbird (hy-AM) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (id) | 141.0 | Mozilla Thunderbird (id) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (is) | 141.0 | Mozilla Thunderbird (is) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (it) | 141.0 | Mozilla Thunderbird (it) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (ja) | 141.0 | Mozilla Thunderbird (ja) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (ka) | 141.0 | Mozilla Thunderbird (ka) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (kab) | 141.0 | Mozilla Thunderbird (kab) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (kk) | 141.0 | Mozilla Thunderbird (kk) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (ko) | 141.0 | Mozilla Thunderbird (ko) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (lt) | 141.0 | Mozilla Thunderbird (lt) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (lv) | 141.0 | Mozilla Thunderbird (lv) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (ms) | 141.0 | Mozilla Thunderbird (ms) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (nb-NO) | 141.0 | Mozilla Thunderbird (nb-NO) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (nl) | 141.0 | Mozilla Thunderbird (nl) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (nn-NO) | 141.0 | Mozilla Thunderbird (nn-NO) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (pa-IN) | 141.0 | Mozilla Thunderbird (pa-IN) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (pl) | 141.0 | Mozilla Thunderbird (pl) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (pt-BR) | 141.0 | Mozilla Thunderbird (pt-BR) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (pt-PT) | 141.0 | Mozilla Thunderbird (pt-PT) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (rm) | 141.0 | Mozilla Thunderbird (rm) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (ro) | 141.0 | Mozilla Thunderbird (ro) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (ru) | 141.0 | Mozilla Thunderbird (ru) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (sk) | 141.0 | Mozilla Thunderbird (sk) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (sl) | 141.0 | Mozilla Thunderbird (sl) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (sq) | 141.0 | Mozilla Thunderbird (sq) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (sr) | 141.0 | Mozilla Thunderbird (sr) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (sv-SE) | 141.0 | Mozilla Thunderbird (sv-SE) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (th) | 141.0 | Mozilla Thunderbird (th) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (tr) | 141.0 | Mozilla Thunderbird (tr) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (uk) | 141.0 | Mozilla Thunderbird (uk) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (uz) | 141.0 | Mozilla Thunderbird (uz) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (vi) | 141.0 | Mozilla Thunderbird (vi) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (zh-CN) | 141.0 | Mozilla Thunderbird (zh-CN) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird (zh-TW) | 141.0 | Mozilla Thunderbird (zh-TW) 141.0 | Jul 22, 2025 |
| Mozilla Thunderbird ESR (af) | 153.0.1 | Mozilla Thunderbird ESR (af) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (ar) | 153.0.1 | Mozilla Thunderbird ESR (ar) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (ast) | 153.0.1 | Mozilla Thunderbird ESR (ast) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (be) | 153.0.1 | Mozilla Thunderbird ESR (be) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (bg) | 153.0.1 | Mozilla Thunderbird ESR (bg) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (br) | 153.0.1 | Mozilla Thunderbird ESR (br) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (ca) | 153.0.1 | Mozilla Thunderbird ESR (ca) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (cak) | 153.0.1 | Mozilla Thunderbird ESR (cak) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (cs) | 153.0.1 | Mozilla Thunderbird ESR (cs) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (cy) | 153.0.1 | Mozilla Thunderbird ESR (cy) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (da) | 153.0.1 | Mozilla Thunderbird ESR (da) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (de) | 153.0.1 | Mozilla Thunderbird ESR (de) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (dsb) | 153.0.1 | Mozilla Thunderbird ESR (dsb) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (el) | 153.0.1 | Mozilla Thunderbird ESR (el) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (en-CA) | 153.0.1 | Mozilla Thunderbird ESR (en-CA) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (en-GB) | 153.0.1 | Mozilla Thunderbird ESR (en-GB) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (en-US) | 140.15.0 | Mozilla Thunderbird ESR (en-US) 140.15.0 | Sep 1, 2026 |
| Mozilla Thunderbird ESR (es-AR) | 153.0.1 | Mozilla Thunderbird ESR (es-AR) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (es-ES) | 153.0.1 | Mozilla Thunderbird ESR (es-ES) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (es-MX) | 153.0.1 | Mozilla Thunderbird ESR (es-MX) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (et) | 153.0.1 | Mozilla Thunderbird ESR (et) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (eu) | 153.0.1 | Mozilla Thunderbird ESR (eu) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (fi) | 153.0.1 | Mozilla Thunderbird ESR (fi) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (fr) | 153.0.1 | Mozilla Thunderbird ESR (fr) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (fy-NL) | 153.0.1 | Mozilla Thunderbird ESR (fy-NL) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (ga-IE) | 153.0.1 | Mozilla Thunderbird ESR (ga-IE) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (gd) | 153.0.1 | Mozilla Thunderbird ESR (gd) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (gl) | 153.0.1 | Mozilla Thunderbird ESR (gl) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (he) | 153.0.1 | Mozilla Thunderbird ESR (he) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (hr) | 153.0.1 | Mozilla Thunderbird ESR (hr) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (hsb) | 153.0.1 | Mozilla Thunderbird ESR (hsb) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (hu) | 153.0.1 | Mozilla Thunderbird ESR (hu) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (hy-AM) | 153.0.1 | Mozilla Thunderbird ESR (hy-AM) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (id) | 153.0.1 | Mozilla Thunderbird ESR (id) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (is) | 153.0.1 | Mozilla Thunderbird ESR (is) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (it) | 153.0.1 | Mozilla Thunderbird ESR (it) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (ja) | 153.0.1 | Mozilla Thunderbird ESR (ja) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (ka) | 153.0.1 | Mozilla Thunderbird ESR (ka) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (kab) | 153.0.1 | Mozilla Thunderbird ESR (kab) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (kk) | 153.0.1 | Mozilla Thunderbird ESR (kk) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (ko) | 153.0.1 | Mozilla Thunderbird ESR (ko) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (lt) | 153.0.1 | Mozilla Thunderbird ESR (lt) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (lv) | 153.0.1 | Mozilla Thunderbird ESR (lv) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (ms) | 153.0.1 | Mozilla Thunderbird ESR (ms) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (nb-NO) | 153.0.1 | Mozilla Thunderbird ESR (nb-NO) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (nl) | 153.0.1 | Mozilla Thunderbird ESR (nl) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (nn-NO) | 153.0.1 | Mozilla Thunderbird ESR (nn-NO) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (pa-IN) | 153.0.1 | Mozilla Thunderbird ESR (pa-IN) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (pl) | 153.0.1 | Mozilla Thunderbird ESR (pl) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (pt-BR) | 153.0.1 | Mozilla Thunderbird ESR (pt-BR) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (pt-PT) | 153.0.1 | Mozilla Thunderbird ESR (pt-PT) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (rm) | 153.0.1 | Mozilla Thunderbird ESR (rm) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (ro) | 153.0.1 | Mozilla Thunderbird ESR (ro) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (ru) | 153.0.1 | Mozilla Thunderbird ESR (ru) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (sk) | 153.0.1 | Mozilla Thunderbird ESR (sk) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (sl) | 153.0.1 | Mozilla Thunderbird ESR (sl) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (sq) | 153.0.1 | Mozilla Thunderbird ESR (sq) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (sr) | 153.0.1 | Mozilla Thunderbird ESR (sr) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (sv-SE) | 153.0.1 | Mozilla Thunderbird ESR (sv-SE) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (th) | 153.0.1 | Mozilla Thunderbird ESR (th) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (tr) | 153.0.1 | Mozilla Thunderbird ESR (tr) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (uk) | 153.0.1 | Mozilla Thunderbird ESR (uk) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (uz) | 153.0.1 | Mozilla Thunderbird ESR (uz) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (vi) | 153.0.1 | Mozilla Thunderbird ESR (vi) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (zh-CN) | 153.0.1 | Mozilla Thunderbird ESR (zh-CN) 153.0.1 | Jul 23, 2026 |
| Mozilla Thunderbird ESR (zh-TW) | 153.0.1 | Mozilla Thunderbird ESR (zh-TW) 153.0.1 | Jul 23, 2026 |
| Linux | |||
| MozillaThunderbird · sles 15.7 | 153.2.0-150400.13.3.1 | SUSE-SU-2026:4268-1 | Sep 18, 2026 |
| thunderbird · Debian 12.15 (bookworm) | 1:140.13.0esr-2~deb12u1 | DEBIAN-CVE-2026-14899 | Aug 8, 2026 |
| thunderbird · Debian 13.5 (trixie) | 1:140.13.0esr-2~deb13u1 | DEBIAN-CVE-2026-14899 | Aug 8, 2026 |
| thunderbird · Debian 14 | 1:140.13.0esr-1 | DEBIAN-CVE-2026-14899 | Aug 8, 2026 |
| thunderbird · RHEL 10 | 140.13.0-1.el10_0 | RHSA-2026:53445 | Aug 3, 2026 |
| thunderbird · RHEL 8 | 0:140.13.0-1.el8_10 | RHSA-2026:49922 | Aug 5, 2026 |
| thunderbird · RHEL 9 | 0:140.13.0-1.el9_8 | RHSA-2026:49921 | Aug 5, 2026 |
| thunderbird · almalinux 10 | 140.13.0-1.el10_2.alma.1 | ALSA-2026:49621 | Aug 3, 2026 |
| thunderbird · almalinux 8 | 140.13.0-1.el8_10.alma.1 | ALSA-2026:49922 | Aug 4, 2026 |
| thunderbird · almalinux 9 | 140.13.0-1.el9_8.alma.1 | ALSA-2026:49921 | Aug 4, 2026 |
| thunderbird · ol 10 | 0:140.13.0-1.0.1.el10_2 | ELSA-2026-49621 | Aug 3, 2026 |
| thunderbird · ol 8 | 0:140.13.0-1.0.1.el8_10 | ELSA-2026-49922 | Aug 4, 2026 |
| thunderbird · ol 9 | 0:140.13.0-1.0.1.el9_8 | ELSA-2026-49921 | Aug 4, 2026 |
| thunderbird · rocky 10 | 0:140.13.0-1.el10_2 | RLSA-2026:49621 | Aug 6, 2026 |
| thunderbird · rocky 8 | 0:140.13.0-1.el8_10 | RLSA-2026:49922 | Aug 6, 2026 |
| thunderbird · rocky 9 | 0:140.13.0-1.el9_8 | RLSA-2026:49921 | Aug 6, 2026 |
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