CVE-2026-31870

HIGHPre-NVD 7.57.5
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (40th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated

Also known asEUVD-2026-11275 (ENISA EUVD)Source: ENISA EUVD

7.5EG
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: 0.5%CVSS: 7.5Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.37.1, when a cpp-httplib client uses the streaming API (httplib::stream::Get, httplib::stream::Post, etc.), the library calls std::stoull() directly on the Content-Length header value received from the server with no input validation and no exception handling. std::stoull throws std::invalid_argument for non-numeric strings and std::out_of_range for values exceeding ULLONG_MAX. Since nothing catches these exceptions, the C++ runtime calls std::terminate(), which kills the process with SIGABRT. Any server the client connects to — including servers reached via HTTP redirects, third-party APIs, or man-in-the-middle positions can crash the client application with a single HTTP response. No authentication is required. No interaction from the end user is required. The crash is deterministic and immediate. This vulnerability is fixed in 0.37.1.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
50
EG Risk 50/100

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)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 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
0.5%
EPSS %ILE
40th
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 (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS. 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

March 11, 2026

Last Modified

June 17, 2026

Advisory Details (1)

Auto-updated Aug 2, 2026
Patch available. Sources: github.
GitHub advisoryMentions a patch (unverified)

Remote Process Crash via Malformed Content-Length Response Header · Advisory · yhirose/cpp-httplib · GitHub

https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-39q5-hh6x-jpxx

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
cpp-httplib0.11.4+ds-1 ... 0.41.0+ds-3~bpo13+1 (27 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
cpp-httplib0.18.7-1 ... 0.41.0+ds-3~bpo13+1 (9 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
cpp-httplib0.18.7-1 ... 0.41.0+ds-3~bpo13+1 (7 versions)
  • every version up to 0.41.0+ds-3: fixed in 0.41.0+ds-3
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 39× 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.

Showing the most recent 95 of 106 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 5 repeat rows among the latest 100 are merged into the row they repeat. The 11 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  2. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  3. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  4. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  5. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  6. 2026-10-28 06:33 UTCEG score recompute
  7. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  8. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  9. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  10. 2026-10-25 14:36 UTCEG score recompute
  11. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  12. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  13. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  14. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  15. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  16. 2026-10-20 09:51 UTCEG score recompute
  17. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  18. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  19. 2026-10-18 03:48 UTCEG score recompute
  20. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  21. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  22. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  23. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  24. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  25. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.6% · 45th percentile
Show 70 more
  1. 2026-10-12 15:49 UTCEG score recompute
  2. 2026-10-11 19:57 UTCEG score recompute
  3. 2026-10-11 17:10 UTCEG score recompute
  4. 2026-10-11 14:38 UTCEG score recompute
  5. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  6. 2026-10-11 11:47 UTCOSV refresh
  7. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  8. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  9. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  10. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  11. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  12. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  13. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  14. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  15. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  16. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  17. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  18. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  19. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  20. 2026-09-22 00:15 UTCOSV refresh
  21. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  22. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  23. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  24. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  25. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  26. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  27. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  28. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  29. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  30. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  31. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  32. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  33. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  34. 2026-09-02 20:10 UTCOSV refresh
  35. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  36. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  37. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  38. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  39. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  40. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  41. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  42. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  43. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  44. 2026-08-24 14:17 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  45. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  46. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  47. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  48. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  49. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  50. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  51. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  52. 2026-08-16 11:52 UTCEG score recompute
  53. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  54. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  55. 2026-08-14 07:50 UTCEG score recompute
  56. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  57. 2026-08-12 23:00 UTCEG score recompute
  58. 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  59. 2026-08-11 21:50 UTCEG score recompute
  60. 2026-08-11 04:58 UTCEG score recompute
  61. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  62. 2026-08-09 20:35 UTCEG score recompute
  63. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  64. 2026-08-09 07:31 UTCEG score recompute
  65. 2026-08-08 16:37 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  66. 2026-08-07 18:17 UTCEG score recompute
  67. 2026-08-06 19:54 UTCEG score recompute
  68. 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  69. 2026-08-06 02:02 UTCEG score recompute
  70. 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.5% · 37th percentile

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Frequently asked(5)

What is CVE-2026-31870?
CVE-2026-31870 is a high-severity vulnerability; its CVE record was published on March 11, 2026. cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.37.1, when a cpp-httplib client uses the streaming API (httplib::stream::Get, httplib::stream::Post, etc.), the library calls std::stoull() directly on the Content-Length header value received from the…
When was the CVE record for CVE-2026-31870 published?
The CVE record for CVE-2026-31870 was published on March 11, 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 June 17, 2026; the record at its source may have been updated since.
Is CVE-2026-31870 actively exploited?
CVE-2026-31870 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (40th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-31870?
CVE-2026-31870 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-31870?
A fix for CVE-2026-31870 is available: update to the fixed version the vendor names in its advisory.

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