CVE-2025-11468: Python Software Foundation CPython · CRLF Injection
Affects Python Software Foundation CPythonSource CVE Database V5
Not known to be exploited · CVSS 5.7 Medium · fixed in 3.15.0a6 : update Python Software Foundation CPython when convenient.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 49% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 3.15.0a6, 3.14.3, 3.13.12 +3
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 20 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Python Software FoundationCPython | Affected
| Fixed in
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| Python Software FoundationCPython | Affected
| Fixed in
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| Python Software FoundationCPython | Affected
| Fixed in
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| Python Software FoundationCPython | Affected
| Fixed in
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| Python Software FoundationCPython | Affected
| Fixed in
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| Python Software FoundationCPython | Affected
| Fixed in
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Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Organizations should monitor for official patches from the Python Software Foundation and apply them promptly once released. If you cannot patch yet, developers should implement strict input validation and sanitization on all user-controlled email address fields to prevent injection of unfoldable characters or malicious payloads. Employing robust email header construction libraries that correctly handle folding and escaping can mitigate risks. Additionally, deploying email security gateways and filters that detect anomalous or malformed headers can provide a secondary defense layer. Restricting privileges for processes handling email generation reduces the attack surface. Conducting code reviews focused on email header handling and incorporating fuzz testing for header parsing logic can help identify similar issues proactively. Finally, educating developers about secure email handling practices and the risks of header injection is essential.
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.
References
- github.com/python/cpython/pull/143936 (opens in a new tab)
- github.com/python/cpython/issues/143935 (opens in a new tab)
- mail.python.org/archives/list/security-announce@python.org/thread/FELSEOLBI2QR6YLG6Q7VYF7FWSGQTKLI/ (opens in a new tab)
- github.com/python/cpython/commit/17d1490aa97bd6b98a42b1a9b324ead84e7fd8a2 (opens in a new tab)
- github.com/python/cpython/commit/61614a5e5056e4f61ced65008d4576f3df34acb6 (opens in a new tab)
- github.com/python/cpython/commit/e9970f077240c7c670e8a6fc6662f2b30d3b6ad0 (opens in a new tab)
- github.com/python/cpython/commit/f738386838021c762efea6c9802c82de65e87796 (opens in a new tab)
- github.com/python/cpython/commit/a76e4cd62dd68e7cbe86e37e6ed988495a646b66 (opens in a new tab)
- github.com/python/cpython/commit/003b8315669b9f08b1010a49071f73f15f818094 (opens in a new tab)