5.9

CVE-2026-91766: php_group php

CVSS: 5.9v3.1MediumAwaiting analysis
AliasesUBUNTU-CVE-2026-91766DEBIAN-CVE-2026-91766
Published 25-09-2026Last modified 28-09-2026

Vulnerability summary

CVE-2026-91766 is a medium (CVSS 5.9) vulnerability in php_group php. EPSS estimates a 0.34% chance of exploitation in the next 30 days, higher than 25.7% of scored vulnerabilities.

Overall risk
24/100
0100
Low · default modelHow is this calculated?
CVSS score
5.9/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.34%
0%100%
Low · Change unavailable
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 9 · Related 6

Timeline

  1. 25-09-2026
    PublishedVulnerability first disclosed.
  2. 28-09-2026
    Last modifiedVulnerability information updated.

Description

When the http:// stream wrapper follows a redirect it forwards the user-supplied Authorization, Cookie and Proxy-Authorization headers unchanged, even when the redirect target is a different host, a different port, or a downgrade from HTTPS to HTTP. A server that can steer a redirect therefore receives credentials that were only meant for the original origin. This is the same class of issue that libcurl fixed in 7.58.0 ( CVE-2018-1000007 https://github.com/advisories/GHSA-g7x2-hrfp-pv5f ).

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.34%

Chance of exploitation in the next 30 days

Percentile

26%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

26-09-202619-10-2026
EPSS score
0.34%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu7 products
  • php5All versions (No fix recorded)
  • php7.0All versions (No fix recorded)
  • php7.2All versions (No fix recorded)
  • php7.4All versions (No fix recorded)
  • php8.1All versions (No fix recorded)
Debian2 products
  • php8.2< 8.2.34-1~deb12u1
  • php8.4< 8.4.26-1~deb13u1 | < 8.4.26-1
Php_group1 product
  • php≥ 8.2.*, < 8.2.34 | ≥ 8.3.*, < 8.3.35 | ≥ 8.4.*, < 8.4.26 | ≥ 8.5.*, < 8.5.11

3 vendors · 10 products

References

6 links