CVE-2026-115877

MEDIUMPre-NVD 5.45.4
EchelonGraph scoreHIGH confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 5.4 from GitHub Security Advisory (severity: MODERATE) published 2026-10-23. A secondary CVSS source baseline 5.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this weekElevated

Also known asEUVD-2026-109153 (ENISA EUVD) · GHSA-q7qq-6mhp-9rc4 (GitHub Security Advisories)Source: ENISA EUVD

5.4EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 5.4Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.web.http.HTTPChannel.headerReceived rejects a NUL byte in an HTTP header value but accepts a bare carriage return or bare line feed. Because Twisted splits header lines only on CRLF, a hidden Content-Length header can remain folded into another value while a lenient front end treats the bare character as a line terminator. The resulting framing disagreement can smuggle a following request past front-end access controls, poison a shared connection or cache, and expose a later client to the wrong response. This issue is an incomplete-fix residual of earlier Twisted request-smuggling protections. This issue is fixed in version 26.10.0rc1.

CVSS v3
5.4
EG Score
5.4MEDIUMhigh confidence
EG Risk
40
EG Risk 40/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity54% × 45%
Impact severity (EG Severity): CVSS 5.4 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.3%
EPSS %ILE
17th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (5.4): severity, escalated by confirmed exploitation. This CVE's 5.4 is its impact severity (EG Severity), not escalated.

EG Severity
5.4 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

October 23, 2026

Last Modified

October 29, 2026

Advisory Details (5)

Auto-updated Oct 23, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_pr, github_release, github.
GitHub advisoryMentions a patch (unverified)🟡 PoC Available

HTTP Request Smuggling in twisted.web via a Bare CR or LF in a Header Value · Advisory · twisted/twisted · GitHub

https://github.com/twisted/twisted/security/advisories/GHSA-q7qq-6mhp-9rc4
GitHub release Patch Available

Towncrier 26.10.0rc1

Patch available: twisted/twisted twisted-26.10.0rc1 (pre-release)

https://github.com/twisted/twisted/releases/tag/twisted-26.10.0rc1
GitHub pull request Patch Available

Reject a bare CR or LF in an HTTP header value (#12754)

Patch available: twisted/twisted twisted-26.10.0rc1 (PR #12755 merged 2026-08-02)

https://github.com/twisted/twisted/pull/12755
GitHub commit Patch Available

commit 1616f702d36e (twisted/twisted)

Patch available: twisted/twisted twisted-26.10.0rc1 (contains commit 1616f702d36e)

https://github.com/twisted/twisted/commit/1616f702d36eda8990a5a5b22ad70fab140a7eb1
GitHub commit Patch Available

commit 022b6f7feb59 (twisted/twisted)

Patch available: twisted/twisted twisted-26.10.0rc1 (contains commit 022b6f7feb59)

https://github.com/twisted/twisted/commit/022b6f7feb5980166c71f54e2c0d8f4f21ff6e1a

Vendor Advisories for CVE-2026-115877(2)

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

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
pipTwisted @ 26.10.0rc1 (fixes <= 26.4.0)—ghsa

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.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
twisted1.0.1 ... 9.0.0 (111 versions)
  • every version up to 26.10.0rc1: fixed in 26.10.0rc1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 20× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  2. 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  3. 2026-11-01 07:59 UTCGHSA enrichmentGHSA-q7qq-6mhp-9rc4 · GitHub severity MODERATE · GitHub CVSS 5.4
  4. 2026-11-01 07:59 UTCEG score recompute
  5. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  6. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  7. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  8. 2026-10-29 15:26 UTCEG score recompute
  9. 2026-10-29 15:26 UTCVendor advisory
  10. 2026-10-29 14:33 UTCEG score recompute
  11. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  12. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  13. 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  14. 2026-10-26 14:08 UTCEG score recompute
  15. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  16. 2026-10-25 14:50 UTCEG score recompute
  17. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  18. 2026-10-23 21:35 UTCEG score recompute
  19. 2026-10-23 20:35 UTCEG score recomputeFirst assessed: 5.4 MEDIUM
  20. 2026-10-23 20:34 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-115877?
CVE-2026-115877 is a medium-severity vulnerability; its CVE record was published on October 23, 2026. Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.web.http.HTTPChannel.headerReceived rejects a NUL byte in an HTTP header value but accepts a bare carriage return or bare line feed. Because Twisted splits header lines only on CRLF,…
When was the CVE record for CVE-2026-115877 published?
The CVE record for CVE-2026-115877 was published on October 23, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 29, 2026; the record at its source may have been updated since.
Is CVE-2026-115877 actively exploited?
CVE-2026-115877 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (17th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-115877?
CVE-2026-115877 has a CVSS base score of 5.4 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-115877?
A fix for CVE-2026-115877 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-115877 are linked in the Vendor Advisories panel on this page.

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