CVE-2026-59881

MEDIUMPre-NVD 6.96.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 77% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
6.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.9Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the WebSocket client accepts and decompresses frames with the RSV1 bit set even when the permessage-deflate extension was not negotiated, allowing a malicious server to cause unexpected CPU and memory consumption. This issue is fixed in version 3.14.2.

CVSS v3
6.9
EG Score
6.9(medium)
EG Risk
31(Track)
EG Risk 31/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity69% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
23%
KEV
Not listed

Published

July 30, 2026

Last Modified

July 30, 2026

Advisory Details (3)

Auto-updated Jul 30, 2026
Patch available. Sources: github, github_pr, github_commit.
github_commit

commit 47fb6ae354d4 (aio-libs/aiohttp)

Fix landed in aio-libs/aiohttp commit 47fb6ae354d4 — awaiting tagged release

https://github.com/aio-libs/aiohttp/commit/47fb6ae354d4fa22048f4dbe7dbf82b625f0a2f6
github_pr

Fix decompressing frames without negotiation (#12976)

Fix merged in aio-libs/aiohttp PR #12978 on 2026-06-23 — awaiting tagged release

https://github.com/aio-libs/aiohttp/pull/12978
github Patch Available

WebSocket client accepts compressed frames without negotiated permessage-deflate · Advisory · aio-libs/aiohttp · GitHub

https://github.com/aio-libs/aiohttp/security/advisories/GHSA-mq44-7p77-q5h7

Vendor Advisories for CVE-2026-59881(1)

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

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
python-aiohttp3.10.0-1 ... 3.9.5-1 (41 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
python-aiohttp3.10.0-1 ... 3.9.5-1 (32 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
python-aiohttp3.11.16-1 ... 3.14.1-4 (14 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
python-aiohttp3.11.16-1 ... 3.14.1-4 (13 versions)——
PyPI(1)
PackageVulnerable rangeFixed inDependents
aiohttp0.1 ... 3.9.5 (308 versions)3.14.2—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 42× 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. 2026-08-20 22:55 UTCEPSS rescore
  2. 2026-08-19 21:47 UTCEG score recompute
  3. 2026-08-19 17:04 UTCEPSS rescore
  4. 2026-08-18 22:52 UTCEG score recompute
  5. 2026-08-18 13:48 UTCEPSS rescore
  6. 2026-08-17 23:58 UTCEG score recompute
  7. 2026-08-17 13:47 UTCEPSS rescore
  8. 2026-08-17 01:04 UTCEG score recompute
  9. 2026-08-16 14:56 UTCEPSS rescore
  10. 2026-08-16 02:14 UTCEPSS rescore
  11. 2026-08-15 03:16 UTCEG score recompute
  12. 2026-08-15 01:30 UTCEPSS rescore
  13. 2026-08-14 04:22 UTCEG score recompute
  14. 2026-08-13 22:00 UTCEPSS rescore
  15. 2026-08-13 05:28 UTCEG score recompute
  16. 2026-08-12 13:51 UTCEPSS rescore
  17. 2026-08-12 06:33 UTCEG score recompute
  18. 2026-08-11 07:38 UTCEG score recompute
  19. 2026-08-11 00:00 UTCEPSS rescore
  20. 2026-08-10 08:44 UTCEG score recompute
  21. 2026-08-09 13:46 UTCEPSS rescore
  22. 2026-08-09 09:50 UTCEG score recompute
  23. 2026-08-08 16:37 UTCEPSS rescore
  24. 2026-08-08 10:56 UTCEG score recompute
  25. 2026-08-07 12:01 UTCEG score recompute
Show 17 more
  1. 2026-08-06 13:47 UTCEPSS rescore
  2. 2026-08-06 13:07 UTCEG score recompute
  3. 2026-08-05 19:17 UTCEPSS rescore
  4. 2026-08-05 14:12 UTCEG score recompute
  5. 2026-08-04 15:10 UTCEPSS rescore
  6. 2026-08-04 14:44 UTCEG score recompute
  7. 2026-08-04 10:39 UTCEPSS rescore
  8. 2026-08-03 15:49 UTCEG score recompute
  9. 2026-08-03 10:36 UTCEPSS rescore
  10. 2026-08-02 16:55 UTCEG score recompute
  11. 2026-08-02 02:27 UTCEPSS rescore
  12. 2026-08-01 18:01 UTCEG score recompute
  13. 2026-08-01 04:16 UTCEPSS rescore
  14. 2026-07-30 19:30 UTCEG score recompute
  15. 2026-07-30 18:57 UTCEG score recompute
  16. 2026-07-30 17:57 UTCEG score recompute
  17. 2026-07-30 17:56 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-59881?
CVE-2026-59881 is a medium vulnerability published on July 30, 2026. AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the WebSocket client accepts and decompresses frames with the RSV1 bit set even when the permessage-deflate extension was not negotiated, allowing a malicious server to cause unexpected CPU and memory…
When was CVE-2026-59881 disclosed?
CVE-2026-59881 was first published in the National Vulnerability Database on July 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-59881 actively exploited?
CVE-2026-59881 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 77.1% of all scored CVEs.
What is the CVSS score of CVE-2026-59881?
CVE-2026-59881 has a CVSS v3 base score of 6.9 (NVD).
How do I remediate CVE-2026-59881?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59881, 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.

Dependency Blast Radius

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