Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Symfony's symfony/mime and symfony/symfony packages are affected in versions below 5.4.52, from 6.0.0 to below 6.4.40, from 7.0.0 to below 7.4.12, and from 8.0.0 to below 8.0.12. The parameter names in structured headers such as Content-Disposition are not validated, so when an application derives a parameter name from untrusted input, an attacker who can influence that name can inject extra headers into the rendered message. The fix is to upgrade to 5.4.52, 6.4.40, 7.4.12, or 8.0.12, depending on the branch in use.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 6.3 | Medium | 4.0 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0039, the 33rd percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 20 May 2026, 10:21 UTC Published by the maintainers as a GitHub repository advisory
- 31 Oct 2026, 13:58 UTC First seen by agentprime
- 31 Oct 2026, 13:58 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-vqc8-7275-q272
- OSV: GHSA-vqc8-7275-q272
- github.com/symfony/symfony/security/advisories/GHSA-vqc8-7275-q272
- github.com/FriendsOfPHP/security-advisories/blob/master/symfony/mime/CVE-2026-45070.yaml
- github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45070.yaml
- github.com/symfony/symfony
- symfony.com/cve-2026-45070