6.3

CVE-2026-58055: nghttp2 nghttpx - HTTP Request/Response Smuggling via Upgrade Request with Content-Length

Analyzed
AliasesALPINE-CVE-2026-58055MGASA-2026-0309SUSE-SU-2026:22594-1
Published 28-06-2026Last modified 29-06-2026

Vulnerability summary

CVE-2026-58055 is a medium (CVSS 6.3) vulnerability in nghttp2. EPSS estimates a 0.25% chance of exploitation in the next 30 days, higher than 16.8% of scored vulnerabilities. 1 public exploit is recorded.

Priority
Routine

Not severe (CVSS 6.3, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
6.3/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.25%
0%100%
Low · -0.07 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits1github

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
RHSA-2026:41240CGA-833V-74CW-P36Q

Timeline

  1. 28-06-2026
    PublishedVulnerability first disclosed.
  2. 29-06-2026
    Last modifiedVulnerability information updated.

Description

nghttp2's nghttpx proxy through 1.69.0 forwards an HTTP/1.1 Upgrade request that also carries a Content-Length header and body onto reusable keep-alive backend connections, re-adding the Upgrade and Connection headers while passing Content-Length verbatim. A backend that resolves the resulting ambiguous message in the attacker's favor enables HTTP request/response smuggling and cross-client response-queue poisoning.

CVSS metrics

11 scores · 8 sources · 2 versions

EPSS trend

Probability

0.25%

Chance of exploitation in the next 30 days

Percentile

17%

Versus all other CVEs

30-day change

Decrease -0.07 pp

From 0.32% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

1 found
  • githubUnverified

    Exploitarium

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Suse10 products
  • nghttp2&distro=SUSE Linux Enterprise Micro 5.3< 1.40.0-150200.25.1
  • nghttp2&distro=SUSE Linux Enterprise Micro 5.4< 1.40.0-150200.25.1
  • nghttp2&distro=SUSE Linux Enterprise Micro 5.5< 1.40.0-150200.25.1
  • nghttp2&distro=SUSE Linux Enterprise Module for Basesystem 15 SP7< 1.40.0-150600.25.8.1 | < 1.64.0-150700.3.6.1
  • nghttp2&distro=SUSE Linux Enterprise Server 16.0< 1.64.0-160000.4.1
Redhat8 products
  • libnghttp2< 0:1.69.0-3.1.hum1 | < 0:1.69.0-5.hum1 | < 0:1.68.0-3.el10_2.2 | < 0:1.43.0-6.el9_8.2 | < 0:1.33.0-6.el8_10.3
  • libnghttp2-debuginfo< 0:1.68.0-3.el10_2.2 | < 0:1.43.0-6.el9_8.2 | < 0:1.33.0-6.el8_10.3
  • libnghttp2-devel< 0:1.69.0-3.1.hum1 | < 0:1.69.0-5.hum1 | < 0:1.68.0-3.el10_2.2 | < 0:1.43.0-6.el9_8.2 | < 0:1.33.0-6.el8_10.3
  • mingw32-libnghttp2< 0:1.69.0-3.1.hum1 | < 0:1.69.0-5.hum1
  • mingw64-libnghttp2< 0:1.69.0-3.1.hum1 | < 0:1.69.0-5.hum1
Chainguard4 products
  • libnghttp2-14< 1.70.0-r0
  • nghttp2< 1.70.0-r0
  • nghttp2-dev< 1.70.0-r0
  • nghttp2-doc< 1.70.0-r0
Wolfi4 products
  • libnghttp2-14< 1.70.0-r0
  • nghttp2< 1.70.0-r0
  • nghttp2-dev< 1.70.0-r0
  • nghttp2-doc< 1.70.0-r0
Mageia2 products
  • nghttp2< 1.68.1-2.1.mga10
  • nghttp2< 1.61.0-1.2.mga9
Opensuse2 products
  • nghttp2&distro=openSUSE Leap 16.0< 1.64.0-160000.4.1
  • nghttp2&distro=openSUSE Tumbleweed< 1.69.0-2.1
Alpine1 product
  • nghttp2< 1.70.0-r0
Debian1 product
  • nghttp2All versions (No fix recorded) | < 1.70.0-1
Nghttp21 product
Ubuntu1 product
  • nghttp2All versions (No fix recorded) | < 1.43.0-1ubuntu0.4 | < 1.59.0-1ubuntu0.4 | < 1.64.0-1.1ubuntu1.2 | < 1.68.0-2ubuntu0.2

10 vendors · 34 products

References

37 links
Show all 37 references