CVE-2026-4271

MEDIUMNVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

Score 5.3 from GitHub Security Advisory published 2026-03-17. NVD baseline CVSS 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Elevated
5.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 5.3Exploit: NoneExposed: 0

A fix is available — apply it.

A flaw was found in libsoup, a library for handling HTTP requests. This vulnerability, known as a Use-After-Free, occurs in the HTTP/2 server implementation. A remote attacker can exploit this by sending specially crafted HTTP/2 requests that cause authentication failures. This can lead to the application attempting to access memory that has already been freed, potentially causing application instability or crashes, resulting in a Denial of Service (DoS).

CVSS v3
5.3
EG Score
5.3(medium)
EPSS
53.4%
KEV
Not listed

Published

March 17, 2026

Last Modified

May 19, 2026

Advisory Details (4)

Auto-updated May 12, 2026
🔬 Proof of concept available. Patch available. Sources: redhat.
generic🟡 PoC Available

(CVE-2026-4271) (#YWH-PGM9867-167) Use After Free on libsoup through libsoup/server/http2/soup-server-message-io-http2.c via "on_frame_recv_callback()" (#496) · Issues · GNOME / libsoup · GitLab

https://gitlab.gnome.org/GNOME/libsoup/-/issues/496
redhat Patch Available

2448044 – (CVE-2026-4271) CVE-2026-4271 libsoup: libsoup: Denial of Service via Use-After-Free in HTTP/2 server

Affected: Red Hat Enterprise Linux 10

https://bugzilla.redhat.com/show_bug.cgi?id=2448044
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-4271
redhat Patch Available

Affected: Red Hat Enterprise Linux 10.

https://access.redhat.com/errata/RHSA-2026:15968

Vendor Advisories for CVE-2026-4271(4)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatlibsoup3-0:3.6.5-3.el10_2.112026-05-19redhat
redhatlibsoup3-0:3.6.5-3.el10_0.152026-05-14redhat
redhatlibsoup3-0:3.6.5-3.el10_1.112026-05-11redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 35× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-19 02:29 UTCEPSS rescore
  2. 2026-07-18 10:04 UTCEPSS rescore
  3. 2026-07-16 17:03 UTCEPSS rescore
  4. 2026-07-15 16:57 UTCEPSS rescore
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  6. 2026-07-15 02:00 UTCEPSS rescore
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  8. 2026-07-13 22:30 UTCEPSS rescore
  9. 2026-07-12 05:46 UTCEPSS rescore
  10. 2026-07-11 08:27 UTCEPSS rescore
  11. 2026-07-09 19:10 UTCEPSS rescore
  12. 2026-07-08 15:16 UTCEPSS rescore
  13. 2026-07-07 13:46 UTCEPSS rescore
  14. 2026-07-06 16:27 UTCEPSS rescore
  15. 2026-07-06 02:23 UTCEPSS rescore
  16. 2026-07-05 02:30 UTCEPSS rescore
  17. 2026-07-04 06:31 UTCEPSS rescore
  18. 2026-07-01 15:07 UTCEPSS rescore
  19. 2026-06-30 23:22 UTCEPSS rescore
  20. 2026-06-28 14:07 UTCEPSS rescore
  21. 2026-06-28 04:56 UTCEPSS rescore
  22. 2026-06-28 04:56 UTCEPSS rescore
  23. 2026-06-27 03:08 UTCEPSS rescore
  24. 2026-06-25 13:49 UTCEPSS rescore
  25. 2026-06-24 14:05 UTCEPSS rescore
Show 64 more
  1. 2026-06-23 21:33 UTCEPSS rescore
  2. 2026-06-23 21:33 UTCEPSS rescore
  3. 2026-06-22 14:25 UTCEPSS rescore
  4. 2026-06-22 14:25 UTCEPSS rescore
  5. 2026-06-21 14:56 UTCEPSS rescore
  6. 2026-06-21 14:56 UTCEPSS rescore
  7. 2026-06-21 01:59 UTCEPSS rescore
  8. 2026-06-21 01:59 UTCEPSS rescore
  9. 2026-06-19 19:26 UTCEPSS rescore
  10. 2026-06-19 19:26 UTCEPSS rescore
  11. 2026-06-18 17:52 UTCEPSS rescore
  12. 2026-06-18 17:52 UTCEPSS rescore
  13. 2026-06-17 17:53 UTCEPSS rescore
  14. 2026-06-16 17:53 UTCEPSS rescore
  15. 2026-06-15 17:49 UTCEPSS rescore
  16. 2026-06-15 17:49 UTCEPSS rescore
  17. 2026-06-14 23:18 UTCEPSS rescore
  18. 2026-06-13 23:00 UTCEPSS rescore
  19. 2026-06-12 23:12 UTCEPSS rescore
  20. 2026-06-12 23:12 UTCEPSS rescore
  21. 2026-06-11 23:53 UTCVendor advisory
  22. 2026-06-11 23:53 UTCGHSA enrichment
  23. 2026-06-11 14:00 UTCEPSS rescore
  24. 2026-06-10 22:19 UTCEPSS rescore
  25. 2026-06-10 15:48 UTCVendor advisory
  26. 2026-06-10 15:48 UTCGHSA enrichment
  27. 2026-06-10 13:22 UTCEPSS rescore
  28. 2026-06-10 13:22 UTCEPSS rescore
  29. 2026-06-09 16:39 UTCVendor advisory
  30. 2026-06-09 16:39 UTCGHSA enrichment
  31. 2026-06-08 14:17 UTCEPSS rescore
  32. 2026-06-08 14:17 UTCEPSS rescore
  33. 2026-06-07 15:25 UTCEPSS rescore
  34. 2026-06-07 15:25 UTCEPSS rescore
  35. 2026-06-07 14:29 UTCVendor advisory
  36. 2026-06-07 14:29 UTCGHSA enrichment
  37. 2026-06-06 13:47 UTCEPSS rescore
  38. 2026-06-06 13:47 UTCEPSS rescore
  39. 2026-06-05 22:47 UTCEPSS rescore
  40. 2026-06-05 06:10 UTCEPSS rescore
  41. 2026-06-05 06:10 UTCEPSS rescore
  42. 2026-06-04 13:12 UTCEPSS rescore
  43. 2026-06-04 13:12 UTCEPSS rescore
  44. 2026-06-02 20:13 UTCEPSS rescore
  45. 2026-06-01 13:52 UTCEPSS rescore
  46. 2026-06-01 13:52 UTCEPSS rescore
  47. 2026-05-31 22:30 UTCEPSS rescore
  48. 2026-05-31 22:30 UTCEPSS rescore
  49. 2026-05-31 00:16 UTCEPSS rescore
  50. 2026-05-31 00:16 UTCEPSS rescore
  51. 2026-05-29 13:44 UTCEPSS rescore
  52. 2026-05-29 13:44 UTCEPSS rescore
  53. 2026-05-28 13:44 UTCEPSS rescore
  54. 2026-05-28 13:44 UTCEPSS rescore
  55. 2026-05-27 13:40 UTCEPSS rescore
  56. 2026-05-27 13:40 UTCEPSS rescore
  57. 2026-05-26 13:44 UTCEPSS rescore
  58. 2026-05-26 07:18 UTCEPSS rescore
  59. 2026-05-21 22:43 UTCEPSS rescore
  60. 2026-05-20 22:38 UTCEPSS rescore
  61. 2026-05-20 21:02 UTCEG score recompute
  62. 2026-05-20 21:02 UTCVendor advisory
  63. 2026-05-20 21:02 UTCGHSA enrichment
  64. 2026-05-20 11:22 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-4271?
CVE-2026-4271 is a medium vulnerability published on March 17, 2026. A flaw was found in libsoup, a library for handling HTTP requests. This vulnerability, known as a Use-After-Free, occurs in the HTTP/2 server implementation. A remote attacker can exploit this by sending specially crafted HTTP/2 requests that cause authentication failures. This can lead to the…
When was CVE-2026-4271 disclosed?
CVE-2026-4271 was first published in the National Vulnerability Database on March 17, 2026, with the most recent update on May 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-4271 actively exploited?
CVE-2026-4271 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 53.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-4271?
CVE-2026-4271 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-4271?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-4271, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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