CVE-2026-1299

MEDIUMNVD 6.06.0
EchelonGraph scoreMEDIUM confidence

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

This medium-severity CVE scores 6.0 under NVD CVSS v3. EPSS exploit probability: 0.6% (46th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3
6.0EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 6.0Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

The email module, specifically the "BytesGenerator" class, didn’t properly quote newlines for email headers when serializing an email message allowing for header injection when an email is serialized. This is only applicable if using "LiteralHeader" writing headers that don't respect email folding rules, the new behavior will reject the incorrectly folded headers in "BytesGenerator".

CVSS v3
6.0
EG Score
6.0MEDIUMmedium confidence
EG Risk
27
EG Risk 27/100

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 (value × EchelonGraph’s weight)
Severity60% × 45%
The EG Score, 6.0 of 10.
Exploitation0.6% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (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
0.6%
EPSS %ILE
46th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

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

Exploitation none (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.

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

January 23, 2026

Last Modified

June 17, 2026

Advisory Details (10)

Auto-updated Aug 7, 2026
Patch available. Sources: github_commit, github_pr.
Web page

Mailman 3 [CVE-2026-1299] email BytesGenerator header injection due to unquoted newlines - Security-announce - python.org

https://mail.python.org/archives/list/[email protected]/thread/6ZZULGALJTITEAGEXLDJE2C6FORDXPBT/
GitHub pull request

gh-144125: email: verify headers are sound in BytesGenerator

Fix merged in python/cpython PR #144126 on 2026-01-23 — awaiting tagged release

https://github.com/python/cpython/pull/144126
Web page

Encode newlines in headers when using ByteGenerator · Issue #144125 · python/cpython · GitHub

https://github.com/python/cpython/issues/144125
GitHub commit

commit e417f05ad77a (python/cpython)

Fix landed in python/cpython commit e417f05ad77a — awaiting tagged release

https://github.com/python/cpython/commit/e417f05ad77a4c30ddc07f99e90fc0cef43e831a
GitHub commit

commit 8cdf6204f4ae (python/cpython)

Fix landed in python/cpython commit 8cdf6204f4ae — awaiting tagged release

https://github.com/python/cpython/commit/8cdf6204f4ae821f32993f8fc6bad0d318f95f36
GitHub commit

commit 842ce19a0c0b (python/cpython)

Fix landed in python/cpython commit 842ce19a0c0b — awaiting tagged release

https://github.com/python/cpython/commit/842ce19a0c0b58d61591e8f6a708c38db1fb94e4
GitHub commit

commit 7877fe424415 (python/cpython)

Fix landed in python/cpython commit 7877fe424415 — awaiting tagged release

https://github.com/python/cpython/commit/7877fe424415bc4a13045e62a90a7277413d8cb9
GitHub commit

commit 0a925ab591c4 (python/cpython)

Fix landed in python/cpython commit 0a925ab591c4 — awaiting tagged release

https://github.com/python/cpython/commit/0a925ab591c45d6638f37b5e57796f36fa0e56d8
GitHub commit

commit 052e55e7d447 (python/cpython)

Fix landed in python/cpython commit 052e55e7d447 — awaiting tagged release

https://github.com/python/cpython/commit/052e55e7d44718fe46cbba0ca995cb8fcc359413
Web page
https://cve.org/CVERecord?id=CVE-2024-6923

Vendor Advisories for CVE-2026-1299(20)

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

Patch Availability(30)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatrhaiis/vllm-spyre-rhel9:17782445462026-05-12redhat
redhatpython3-12-main-3.12.13-3.hum12026-04-17redhat
redhatrhaiis/vllm-rocm-rhel9:17756802622026-04-17redhat
redhatrhaiis/vllm-cuda-rhel9:17756801922026-04-17redhat
redhatpython3-11-main-3.11.15-4.hum12026-04-17redhat
redhatrhaiis/model-opt-cuda-rhel9:17757498572026-04-17redhat
redhatpython3-14-main-3.14.4-1.hum12026-04-11redhat
redhatpython3-13-main-3.13.13-1.hum12026-04-10redhat
redhatdiscovery/discovery-ui-rhel9:17756759222026-04-09redhat
redhatpython3-0:3.6.8-21.el7_9.42026-04-02redhat
redhatpython3.11-0:3.11.7-1.el9_4.112026-03-31redhat
redhatpython3-0:3.6.8-51.el8_8.132026-03-30redhat
redhatrhceph/rhceph-8-rhel9:17740028672026-03-24redhat
redhatpython3.9-0:3.9.16-1.el9_2.122026-03-23redhat
redhatpython3.9-0:3.9.10-4.el9_0.92026-03-23redhat
redhatpython3-0:3.6.8-39.el8_4.92026-03-23redhat
redhatpython3.11-0:3.11.2-2.el9_2.102026-03-23redhat
redhatpython3.12-0:3.12.9-2.el10_0.72026-03-23redhat
redhatpython3-0:3.6.8-24.el8_2.62026-03-23redhat
redhatpython3.9-0:3.9.18-3.el9_4.112026-03-23redhat
redhatpython3.12-0:3.12.1-4.el9_4.112026-03-23redhat
redhatpython3.9-0:3.9.21-2.el9_6.42026-03-23redhat
redhatpython3-0:3.6.8-47.el8_6.112026-03-23redhat
redhatpython3.11-0:3.11.2-2.el8_8.82026-03-19redhat
redhatrhui5/rhua-rhel9:17736701372026-03-18redhat
redhatpython3.12-0:3.12.12-3.el10_1.12026-03-17redhat
redhatpython3.12-0:3.12.9-1.el9_6.62026-03-17redhat
redhatpython3.11-0:3.11.13-5.el8_102026-03-12redhat
redhatpython3.12-0:3.12.12-3.el8_102026-03-12redhat
redhatpython3.12-0:3.12.12-4.el9_7.12026-03-10redhat

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

(9 across 4 ecosystems)
Debian:14(3)
PackageVulnerable rangeFix by version rangeDependents
pypy37.3.19+dfsg-2, 7.3.20+dfsg-1, 7.3.20+dfsg-2, 7.3.20+dfsg-3, 7.3.20+dfsg-4
  • every version up to 7.3.21+dfsg-1: fixed in 7.3.21+dfsg-1
—
python3.133.13.11-1 ... 3.13.9-1 (6 versions)
  • every version up to 3.13.12-1: fixed in 3.13.12-1
—
python3.143.14.0-1 ... 3.14.2-1 (14 versions)
  • every version up to 3.14.3-1: fixed in 3.14.3-1
—
Debian:11(2)
PackageVulnerable rangeFix by version rangeDependents
pypy37.3.10+dfsg-1 ... 7.3.9+dfsg-5 (53 versions)
  • every version on: no fix on record
—
python3.93.9.2-1, 3.9.2-1+deb11u1, 3.9.2-1+deb11u2, 3.9.2-1+deb11u3, 3.9.2-1+deb11u4
  • every version up to 3.9.2-1+deb11u5: fixed in 3.9.2-1+deb11u5
—
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
pypy37.3.11+dfsg-2 ... 8.0.0+dfsg-1 (31 versions)
  • every version on: no fix on record
—
python3.113.11.2-6 ... 3.11.2-6+deb12u6 (7 versions)
  • every version up to 3.11.2-6+deb12u7: fixed in 3.11.2-6+deb12u7
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
pypy37.3.19+dfsg-2 ... 8.0.0+dfsg-1 (13 versions)
  • every version on: no fix on record
—
python3.133.13.5-2
  • every version up to 3.13.5-2+deb13u1: fixed in 3.13.5-2+deb13u1
—

Weakness Classification(1)

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

Additional Vendor Advisories

(13)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 11× in last 7d / 26× 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 96 of 199 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. 4 repeat rows among the latest 100 are merged into the row they repeat. The 103 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  2. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  3. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  4. 2026-10-12 16:36 UTCEG score recompute
  5. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  6. 2026-10-11 20:12 UTCEG score recompute
  7. 2026-10-11 18:24 UTCEG score recompute
  8. 2026-10-11 14:57 UTCEG score recompute
  9. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  10. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  11. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  12. 2026-10-08 19:24 UTCOSV refresh
  13. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  14. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  15. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  16. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  17. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  18. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  19. 2026-09-29 15:21 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  20. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  21. 2026-09-27 13:47 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  22. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  23. 2026-09-19 01:06 UTCOSV refresh
  24. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  25. 2026-09-16 14:07 UTCEPSS rescoreEPSS 0.5% · 44th percentile
Show 71 more
  1. 2026-09-16 05:14 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  2. 2026-09-13 16:46 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  3. 2026-09-12 15:00 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  4. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  5. 2026-09-11 09:36 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  6. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  7. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  8. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  9. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  10. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  11. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  12. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  13. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  14. 2026-08-31 04:54 UTCOSV refresh
  15. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  16. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  17. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  18. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  19. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  20. 2026-08-25 13:48 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  21. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  22. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  23. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  24. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  25. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  26. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  27. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  28. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  29. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  30. 2026-08-14 12:24 UTCEG score recompute
  31. 2026-08-14 12:24 UTCVendor advisory
  32. 2026-08-14 12:24 UTCGHSA enrichmentGHSA-jh94-8q48-f3m3
  33. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  34. 2026-08-13 04:54 UTCEG score recompute
  35. 2026-08-13 04:54 UTCVendor advisory
  36. 2026-08-13 04:54 UTCGHSA enrichmentGHSA-jh94-8q48-f3m3
  37. 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  38. 2026-08-11 13:42 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  39. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  40. 2026-08-09 18:26 UTCEG score recompute
  41. 2026-08-09 18:26 UTCVendor advisory
  42. 2026-08-09 18:26 UTCGHSA enrichmentGHSA-jh94-8q48-f3m3
  43. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  44. 2026-08-08 16:37 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  45. 2026-08-07 23:37 UTCEG score recompute
  46. 2026-08-07 23:37 UTCVendor advisory
  47. 2026-08-07 23:37 UTCGHSA enrichmentGHSA-jh94-8q48-f3m3
  48. 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  49. 2026-08-06 05:02 UTCEG score recompute
  50. 2026-08-06 05:02 UTCVendor advisory
  51. 2026-08-06 05:02 UTCGHSA enrichmentGHSA-jh94-8q48-f3m3
  52. 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  53. 2026-08-04 15:10 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  54. 2026-08-04 10:38 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  55. 2026-08-03 10:35 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  56. 2026-08-02 22:12 UTCEG score recompute
  57. 2026-08-02 22:12 UTCVendor advisory
  58. 2026-08-02 22:12 UTCGHSA enrichmentGHSA-jh94-8q48-f3m3
  59. 2026-08-02 02:26 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  60. 2026-08-01 04:15 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  61. 2026-07-31 07:12 UTCOSV refresh
  62. 2026-07-30 01:30 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  63. 2026-07-27 14:13 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  64. 2026-07-26 14:54 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  65. 2026-07-25 14:17 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  66. 2026-07-24 14:17 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  67. 2026-07-23 14:18 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  68. 2026-07-23 03:05 UTCEG score recompute
  69. 2026-07-22 14:08 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  70. 2026-07-21 15:24 UTCEPSS rescoreEPSS 0.6% · 42nd percentile
  71. 2026-07-20 17:08 UTCEPSS rescoreEPSS 0.6% · 42nd percentile

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-1299?
CVE-2026-1299 is a medium-severity vulnerability; its CVE record was published on January 23, 2026. The email module, specifically the "BytesGenerator" class, didn’t properly quote newlines for email headers when serializing an email message allowing for header injection when an email is serialized. This is only applicable if using "LiteralHeader" writing headers that don't respect email folding…
When was the CVE record for CVE-2026-1299 published?
The CVE record for CVE-2026-1299 was published on January 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 June 17, 2026; the record at its source may have been updated since.
Is CVE-2026-1299 actively exploited?
CVE-2026-1299 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (46th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-1299?
CVE-2026-1299 has a CVSS v3 base score of 6.0 (NVD).
How do I remediate CVE-2026-1299?
A fix for CVE-2026-1299 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-1299 are linked in the Vendor Advisories panel on this page.

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