Description
When folding a long comment in an email header containing exclusively unfoldable characters, the parenthesis would not be preserved. This could be used for injecting headers into email messages where addresses are user-controlled and not sanitized.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Python Software Foundation | CPython | < 3.10.20, 3.11.0 – < 3.11.15, 3.12.0 – < 3.12.13, 3.13.0 – < 3.13.12, 3.14.0 – < 3.14.3, 3.15.0a1 – < 3.15.0a6 | 3.10.20 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | pypy3 | 7.3.21+dfsg-1 | — |
| Debian 14 | python3.14 | 3.14.3-1 | — |
| Debian 13 | pypy3 | No fix yet | — |
| Debian 13 | python3.13 | 3.13.5-2+deb13u1 | — |
| Debian 12 | pypy3 | No fix yet | — |
| Debian 12 | python3.11 | 3.11.2-6+deb12u7 | — |
| Debian 11 | python3.9 | 3.9.2-1+deb11u5 | DLA-4455-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.10 | python3.13 | 3.13.7-1ubuntu0.3 | — |
| Ubuntu 25.10 | python3.14 | 3.14.0-1ubuntu0.2 | — |
| Ubuntu 24.04 LTS | python3.12 | 3.12.3-1ubuntu0.11 | — |
| Ubuntu 22.04 LTS | python3.10 | 3.10.12-1~22.04.14 | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | python3.11 | 3.11.0~rc1-1~22.04.1~esm8 | — |
| Ubuntu Pro 20.04 LTS | python3.8 | 3.8.10-0ubuntu1~20.04.18+esm5 | — |
| Ubuntu Pro 20.04 LTS | python3.9 | 3.9.5-3ubuntu0~20.04.1+esm9 | — |
| Ubuntu Pro 18.04 LTS | python3.6 | 3.6.9-1~18.04ubuntu1.13+esm8 | — |
| Ubuntu Pro 18.04 LTS | python3.7 | 3.7.5-2ubuntu1~18.04.2+esm9 | — |
| Ubuntu Pro 18.04 LTS | python3.8 | 3.8.0-3ubuntu1~18.04.2+esm9 | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Hardened Images 1 | python3 +15 | 3.14.4-1.hum1 | RHSA-2026:7661 |
| Red Hat Hardened Images 1 | python3.11 +6 | 3.11.15-4.hum1 | RHSA-2026:8822 |
| Red Hat Hardened Images 1 | python3.12 +6 | 3.12.13-3.hum1 | RHSA-2026:8824 |
| Red Hat Hardened Images 1 | python3.13 +8 | 3.13.13-1.hum1 | RHSA-2026:7443 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLES 15 SP7 | python311-core | 3.11.14-150600.3.44.1 | SUSE-SU-2026:1349-1, SUSE-SU-2026:0767-1 |
| SLES 15 SP6 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLES 15 SP6 | python311 +1 | 3.11.14-150600.3.44.1 | SUSE-SU-2026:1349-1, SUSE-SU-2026:0767-1 |
| SLES 15 SP6 | python312 +1 | 3.12.12-150600.3.43.1 | SUSE-SU-2026:0644-1 |
| SLES 15 SP5 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLES 15 SP5 | python311 +2 | 3.11.14-150400.9.75.1 | SUSE-SU-2026:1117-1, SUSE-SU-2026:0693-1 |
| SLES 15 SP5 | python39 +1 | 3.9.25-150300.4.93.1 | SUSE-SU-2026:0643-1 |
| SLES 15 SP4 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLES 15 SP4 | python310 +1 | 3.10.19-150400.4.97.1 | SUSE-SU-2026:0613-1 |
| SLES 15 SP4 | python311 +2 | 3.11.14-150400.9.75.1 | SUSE-SU-2026:1117-1, SUSE-SU-2026:0693-1 |
| SLES 12 SP5 | python3 +1 | 3.4.10-25.172.1 | SUSE-SU-2026:0645-1 |
| SLES 12 SP5 | python36 +1 | 3.6.15-100.1 | SUSE-SU-2026:0612-1 |
Show 15 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 3 | python311 +1 | 3.11.14-150600.3.44.1 | SUSE-SU-2026:1349-1, SUSE-SU-2026:0767-1 |
| SLES 3 | python313 +1 | 3.13.12-150700.4.39.1 | SUSE-SU-2026:0642-1 |
| SLES for SAP 16.0 | python313 +2 | 3.13.12-160000.1.1 | SUSE-SU-2026:20581-1 |
| SLES for SAP 15 SP6 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLES for SAP 15 SP6 | python311 +1 | 3.11.14-150600.3.44.1 | SUSE-SU-2026:1349-1, SUSE-SU-2026:0767-1 |
| SLES for SAP 15 SP6 | python312 +1 | 3.12.12-150600.3.43.1 | SUSE-SU-2026:0644-1 |
| SLES for SAP 15 SP5 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLES for SAP 15 SP5 | python311 +2 | 3.11.14-150400.9.75.1 | SUSE-SU-2026:1117-1, SUSE-SU-2026:0693-1 |
| SLES for SAP 15 SP5 | python39 +1 | 3.9.25-150300.4.93.1 | SUSE-SU-2026:0643-1 |
| SLES for SAP 15 SP4 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLES for SAP 15 SP4 | python310 +1 | 3.10.19-150400.4.97.1 | SUSE-SU-2026:0613-1 |
| SLES for SAP 15 SP4 | python311 +2 | 3.11.14-150400.9.75.1 | SUSE-SU-2026:1117-1, SUSE-SU-2026:0693-1 |
| SLES 16.0 | python313 +2 | 3.13.12-160000.1.1 | SUSE-SU-2026:20581-1 |
| SLE Micro 6.2 | python313 +1 | 3.13.12-160000.1.1 | SUSE-SU-2026:20543-1 |
| SLE Micro 6.1 | python311 +1 | 3.11.14-slfo.1.1_3.1 | SUSE-SU-2026:20768-1, SUSE-SU-2026:20665-1 |
| SLE Micro 6.0 | python311 +1 | 3.11.14-3.1 | SUSE-SU-2026:20796-1, SUSE-SU-2026:20710-1 |
| SLE Micro 5.5 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLE Micro 5.4 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLE Micro 5.3 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLE Micro 5.2 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLE HPC 15 SP5 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLE HPC 15 SP5 | python311 +2 | 3.11.14-150400.9.75.1 | SUSE-SU-2026:1117-1, SUSE-SU-2026:0693-1 |
| SLE HPC 15 SP4 | python3 +1 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| SLE HPC 15 SP4 | python310 +1 | 3.10.19-150400.4.97.1 | SUSE-SU-2026:0613-1 |
| SLE HPC 15 SP4 | python311 +2 | 3.11.14-150400.9.75.1 | SUSE-SU-2026:1117-1, SUSE-SU-2026:0693-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python310 | 3.10.19-4.1 | openSUSE-SU-2026:10200-1 |
| openSUSE Tumbleweed | python311 | 3.11.14-4.1 | openSUSE-SU-2026:10221-1 |
| openSUSE Tumbleweed | python312 | 3.12.12-5.1 | openSUSE-SU-2026:10222-1 |
| openSUSE Tumbleweed | python313 | 3.13.12-1.1 | openSUSE-SU-2026:10223-1 |
| openSUSE Tumbleweed | python314 | 3.14.2-2.1 | openSUSE-SU-2026:10117-1 |
| openSUSE Tumbleweed | python315 | 3.15.0~a3-3.1 | openSUSE-SU-2026:10126-1 |
| openSUSE Leap 16.0 | python313 +4 | 3.13.12-160000.1.1 | openSUSE-SU-2026:20254-1 |
| openSUSE Leap 15.6 | python3 +2 | 3.6.15-150300.10.106.1 | SUSE-SU-2026:0664-1 |
| openSUSE Leap 15.6 | python310 +2 | 3.10.19-150400.4.97.1 | SUSE-SU-2026:0613-1 |
| openSUSE Leap 15.6 | python311 +2 | 3.11.14-150600.3.44.1 | SUSE-SU-2026:1349-1, SUSE-SU-2026:0767-1 |
| openSUSE Leap 15.6 | python312 +2 | 3.12.12-150600.3.43.1 | SUSE-SU-2026:0644-1 |
| openSUSE Leap 15.6 | python39 +2 | 3.9.25-150300.4.93.1 | SUSE-SU-2026:0643-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | python3 +7 | 3.9.25-1.amzn2023.0.4 | ALAS2023-2026-1583 |
| Amazon Linux 2023 | python3.11 +6 | 3.11.14-1.amzn2023.0.4 | ALAS2023-2026-1447 |
| Amazon Linux 2023 | python3.12 +6 | 3.12.12-2.amzn2023.0.4 | ALAS2023-2026-1444 |
| Amazon Linux 2023 | python3.13 +8 | 3.13.12-1.amzn2023.0.1 | ALAS2023-2026-1437 |
| Amazon Linux 2 | python +6 | 2.7.18-1.amzn2.0.16 | ALAS2-2026-3185 |
| Amazon Linux 2 | python3 +6 | 3.7.16-1.amzn2.0.23 | ALAS2-2026-3184 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | python3 | 3.12.9-8 | — |
| Azure Linux 2 (CBL-Mariner) | python3 | No fix yet | — |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | python-3.10 | 3.10.19-r4 | — |
| Wolfi rolling | python-3.11 | 3.11.14-r5 | — |
| Wolfi rolling | python-3.12 | 3.12.12-r5 | — |
| Wolfi rolling | python-3.13 | 3.13.12-r1 | — |
| Wolfi rolling | python-3.14 | 3.14.3-r1 | — |
Advisories 38
- WID-SEC-2026-2189 Dell PowerProtect Data Domain: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 2, 2026
- RHSA-2026:8824 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2026:8822 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2026:7661 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 16, 2026
- RHSA-2026:7443 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 16, 2026
- WID-SEC-2026-0209 Cpython: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 7, 2026
- SUSE-SU-2026:1117-1 Security update for python311 SUSE / openSUSE Security Updates · Sep 18, 2026
- WID-SEC-2026-0778 Dell Secure Connect Gateway Policy Manager: Mehrere Schwachstellen BSI CERT-Bund (WID) · May 11, 2026
- SUSE-SU-2026:1349-1 Security update for python311 SUSE / openSUSE Security Updates · Apr 16, 2026
- ALAS2023-2026-1583 Important: python3.9 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Apr 13, 2026
- SUSE-SU-2026:20768-1 Security update for python311 SUSE / openSUSE Security Updates · Mar 25, 2026
- SUSE-SU-2026:20796-1 Security update for python311 SUSE / openSUSE Security Updates · Mar 25, 2026
- openSUSE-SU-2026:20254-1 Security update for python313 SUSE / openSUSE Security Updates · Mar 23, 2026
- openSUSE-SU-2026:10221-1 python311-3.11.14-4.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- openSUSE-SU-2026:10222-1 python312-3.12.12-5.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- openSUSE-SU-2026:10223-1 python313-3.13.12-1.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- openSUSE-SU-2026:10200-1 python310-3.10.19-4.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- openSUSE-SU-2026:10126-1 python315-3.15.0~a3-3.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- openSUSE-SU-2026:10117-1 python314-3.14.2-2.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:20710-1 Security update for python311 SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:20665-1 Security update for python311 SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:20543-1 Security update for python313 SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:20581-1 Security update for python313 SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:0693-1 Security update for python311 SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:0664-1 Security update for python3 SUSE / openSUSE Security Updates · Mar 23, 2026
- ALAS2-2026-3184 Moderate: python3 security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Mar 5, 2026
- ALAS2-2026-3185 Moderate: python security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Mar 5, 2026
- ALAS2023-2026-1447 Moderate: python3.11 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Mar 5, 2026
- SUSE-SU-2026:0767-1 Security update for python311 SUSE / openSUSE Security Updates · Mar 4, 2026
- SUSE-SU-2026:0645-1 Security update for python3 SUSE / openSUSE Security Updates · Feb 26, 2026
- SUSE-SU-2026:0642-1 Security update for python313 SUSE / openSUSE Security Updates · Feb 26, 2026
- SUSE-SU-2026:0643-1 Security update for python39 SUSE / openSUSE Security Updates · Feb 26, 2026
- SUSE-SU-2026:0644-1 Security update for python312 SUSE / openSUSE Security Updates · Feb 26, 2026
- SUSE-SU-2026:0612-1 Security update for python36 SUSE / openSUSE Security Updates · Feb 26, 2026
- SUSE-SU-2026:0613-1 Security update for python310 SUSE / openSUSE Security Updates · Feb 26, 2026
- ALAS2023-2026-1437 Moderate: python3.13 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Feb 18, 2026
- ALAS2023-2026-1444 Moderate: python3.12 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Feb 18, 2026
- DLA-4455-1 python3.9 - security update Debian Security (DSA / DLA) · Jan 25, 2026
References
- https://github.com/python/cpython/pull/143936 patch
- https://github.com/python/cpython/issues/143935 issue-tracking
- https://mail.python.org/archives/list/security-announce@python.org/thread/FELSEOLBI2QR6YLG6Q7VYF7FWSGQTKLI/ vendor-advisory
- https://github.com/python/cpython/commit/17d1490aa97bd6b98a42b1a9b324ead84e7fd8a2 patch
- https://github.com/python/cpython/commit/61614a5e5056e4f61ced65008d4576f3df34acb6 patch
- https://github.com/python/cpython/commit/e9970f077240c7c670e8a6fc6662f2b30d3b6ad0 patch
- https://github.com/python/cpython/commit/f738386838021c762efea6c9802c82de65e87796 patch
- https://github.com/python/cpython/commit/a76e4cd62dd68e7cbe86e37e6ed988495a646b66 patch
- https://github.com/python/cpython/commit/003b8315669b9f08b1010a49071f73f15f818094 patch