Skip to content
Fencer Intel
high 8.7

CVE-2026-108082 json

Symfony: ReDoS in HeaderUtils::split() Reachable Through the Cache-Control Request Header

published 25d ago modified 13d ago also GHSA-r925-mgvr-h9cc , EUVD-2026-102102

cvss
8.7
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to versions 5.4.54, 6.4.46, 7.4.19, and 8.1.7, HeaderUtils::split() parsed header values with a pattern whose token alternative also matched whitespace, followed by a (?<!\s) lookbehind. A run of whitespace placed before a separator could be divided among the iterations of the enclosing repetition in exponentially many ways, and the engine tried all of them before settling. HeaderBag calls it for the Cache-Control header whenever a Request is built, so any application handling HTTP requests is reachable, with no authentication.

A single request carrying such a header costs close to a second of CPU (813 ms for a run of 17 spaces in an 8 KB header on PHP 8.5, doubling with each extra space). From 18 spaces on, preg_match_all() gives up at pcre.backtrack_limit and split() returns an empty array, so every directive of the header is silently dropped.

This issue affects symfony/http-foundation v4.1.0-BETA1 through v5.4.53, v6.0.0-BETA1 through v6.4.45, v7.0.0-BETA1 through v7.4.18, and v8.0.0-BETA1 through v8.1.6.

Patch / fix

  • packagist symfony/http-foundation 5.4.54, 6.4.46, 7.4.19, 8.1.7
  • packagist symfony/symfony 5.4.54, 6.4.46, 7.4.19, 8.1.7
  • symfony Debian 13 6.4.49+dfsg-0+deb13u1
  • symfony Debian 14 7.4.19+dfsg-1

debian advisories DEBIAN-CVE-2026-108082

Is CVE-2026-108082 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-108082 updated cvss 7.5

symfony/http-foundation: symfony/http-foundation: Denial of Service via crafted HTTP headers

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
25d ago

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
packagist symfony/http-foundation
>=6.0.1, <6.4.46
>=7.0.0, <7.4.19
>=8.0.0, <8.1.7
>=4.1.0, <5.4.54
6.4.46
7.4.19
8.1.7
5.4.54
packagist symfony/symfony
>=6.0.1, <6.4.46
>=7.0.0, <7.4.19
>=8.0.0, <8.1.7
>=4.1.0, <5.4.54
6.4.46
7.4.19
8.1.7
5.4.54

Affected products

  • sensiolabs symfony

Classification

Weakness
  • CWE-1333 Inefficient Regular Expression Complexity

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.