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CVE-2026-25793

Nebula Has Possible Blocklist Bypass via ECDSA Signature Malleability

7.6 HighFix available

Nebula is a scalable overlay networking tool. In versions from 1.7.0 to 1.10.2, when using P256 certificates (which is not the default configuration), it is possible to evade a blocklist entry created against the fingerprint of a certificate by using ECDSA Signature Malleability to use a copy of the certificate with a different fingerprint. This issue has been patched in version 1.10.3.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
None

Exploit likelihood

0.14%Up 0.1 points since Feb 7, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.6

Nebula Has Possible Blocklist Bypass via ECDSA Signature Malleability

Nebula is a scalable overlay networking tool. In versions from 1.7.0 to 1.10.2, when using P256 certificates (which is not the default configuration), it is possible to evade a blocklist entry created against the fingerprint of a certificate by using ECDSA Signature Malleability to use a copy of the certificate with a different fingerprint. This issue has been patched in version 1.10.3.

Record
CVE-2026-25793
CVSS 4.0
7.6 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-347
Updated
2026-11-02
EUVDEUVD-2026-6933 7.6

Nebula is a scalable overlay networking tool. In versions from 1.7.0 to 1.10.2, when using P256 certificates (which is not the default configuration), it is possible to evade a blocklist entry created against the fingerprint of a certificate by using ECDSA Signature Malleability to use a copy of the certificate with a different fingerprint. This issue has been patched in version 1.10.3.

Record
EUVD-2026-6933
CVSS 4.0
7.6 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-69x3-g4r3-p962 7.6

Blocklist Bypass possible via ECDSA Signature Malleability

Impact

When using P256 certificates (which is not the default configuration), it is possible to evade a blocklist entry created against the fingerprint of a certificate by using ECDSA Signature Malleability to use a copy of the certificate with a different fingerprint.

In order for this to affect a user or network, all of the following must be true:

  • CURVE_P256 certificates are being used
  • There are one or more entries on the blocklist
  • The certificates for those entries are signed by a trusted CA and not expired
  • An attacker has a copy of the private key, and corresponding certificate, for one of those blocklist entries

Patches

See attached

Workarounds

If full copies of each certificate on the existing blocklist are available, it is possible to compute their opposite-chirality signature, and then the appropriate second fingerprint to list in the blocklist.

Rotating out all CAs that have signed hosts on the blocklist will also prevent exploitation of this vulnerability.

Record
GHSA-69x3-g4r3-p962
CVSS 4.0
7.6 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-347
Updated
2026-11-02
NVD 7.6

Nebula is a scalable overlay networking tool. In versions from 1.7.0 to 1.10.2, when using P256 certificates (which is not the default configuration), it is possible to evade a blocklist entry created against the fingerprint of a certificate by using ECDSA Signature Malleability to use a copy of the certificate with a different fingerprint. This issue has been patched in version 1.10.3.

Record
CVE-2026-25793
CVSS 4.0
7.6 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Weakness
CWE-347
Updated
2026-11-02
OSV 7.6

Nebula Has Possible Blocklist Bypass via ECDSA Signature Malleability

Nebula is a scalable overlay networking tool. In versions from 1.7.0 to 1.10.2, when using P256 certificates (which is not the default configuration), it is possible to evade a blocklist entry created against the fingerprint of a certificate by using ECDSA Signature Malleability to use a copy of the certificate with a different fingerprint. This issue has been patched in version 1.10.3.

Record
CVE-2026-25793
CVSS 4.0
7.6 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-347
Updated
2026-11-02
OSVGHSA-69x3-g4r3-p962 7.6

Blocklist Bypass possible via ECDSA Signature Malleability

Impact

When using P256 certificates (which is not the default configuration), it is possible to evade a blocklist entry created against the fingerprint of a certificate by using ECDSA Signature Malleability to use a copy of the certificate with a different fingerprint.

In order for this to affect a user or network, all of the following must be true:

  • CURVE_P256 certificates are being used
  • There are one or more entries on the blocklist
  • The certificates for those entries are signed by a trusted CA and not expired
  • An attacker has a copy of the private key, and corresponding certificate, for one of those blocklist entries

Patches

See attached

Workarounds

If full copies of each certificate on the existing blocklist are available, it is possible to compute their opposite-chirality signature, and then the appropriate second fingerprint to list in the blocklist.

Rotating out all CAs that have signed hosts on the blocklist will also prevent exploitation of this vulnerability.

Record
GHSA-69x3-g4r3-p962
CVSS 4.0
7.6 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-347
Updated
2026-11-02
OSVGO-2026-4458 No score

Blocklist Bypass possible via ECDSA Signature Malleability in github.com/slackhq/nebula

Blocklist Bypass possible via ECDSA Signature Malleability in github.com/slackhq/nebula

Record
GO-2026-4458
Updated
2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

  • Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
  • GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
  • GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
  • GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
  • GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
  • GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
  • GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
  • GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
  • GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
  • GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
  • GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
  • GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
  • GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
  • GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
  • GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
  • GO-2026-5933 GHSA-3g4q-2f67-2gvh
  • GO-2026-5934 GHSA-59qp-cfj3-rp64
  • GO-2026-5935 GHSA-7856-g3gv-9wq8
  • GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
  • GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
  • GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
  • GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
  • GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
  • GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
  • GO-2026-5942 CVE-2026-46600
  • GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
  • GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
  • GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
  • GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
  • GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
  • GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
  • GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
  • GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
  • GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
  • GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
  • GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
  • GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
  • GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
  • GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
  • GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
  • GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
  • GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
  • GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
  • GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
  • GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
  • GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
  • GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
  • GO-2026-5969 GHSA-g936-7jqj-mwv8
  • GO-2026-5970 CVE-2026-56852
  • GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
  • GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
  • GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
  • GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
  • GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
  • GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
  • GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
  • GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
  • GO-2026-5981 GHSA-mqxv-9rm6-w8qc
  • GO-2026-5982 GHSA-pqg7-v6wh-3pfp
  • GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
  • GO-2026-5985 GHSA-7rx3-5wx3-5v76
  • GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
  • GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
  • GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
  • GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
  • GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
  • GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
  • GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
  • GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
  • GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
  • GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
  • GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
  • GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
  • GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
  • GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
  • GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
  • GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
Record
openSUSE-SU-2026:21483-1
Updated
2026-11-02
OSVSUSE-SU-2026:0757-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

Update to version 0.0.20260226T182644 2026-02-26T18:26:44Z (jsc#PED-11136) Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2025-4259 CVE-2025-13767 GHSA-fmqf-pmcm-8cx9
  • GO-2025-4260 CVE-2025-64641 GHSA-vww6-79rv-3j4x
  • GO-2026-4282 CVE-2017-18873 GHSA-x6mw-hf2j-vqpc
  • GO-2026-4305 CVE-2017-18903 GHSA-fcwg-45jh-5qhf
  • GO-2026-4325 CVE-2025-14822 GHSA-9r42-rhw3-2222
  • GO-2026-4326 CVE-2025-14435 GHSA-mx8m-v8qm-xwr8
  • GO-2026-4332 CVE-2026-23644 GHSA-2657-3c98-63jq
  • GO-2026-4348 CVE-2026-23991 GHSA-846p-jg2w-w324
  • GO-2026-4349 CVE-2026-23992 GHSA-fphv-w9fq-2525
  • GO-2026-4377 CVE-2026-24686 GHSA-jqc5-w2xx-5vq4
  • GO-2026-4410 CVE-2026-25140 GHSA-f4w5-5xv9-85f6
  • GO-2026-4502 CVE-2026-25766 GHSA-pgvm-wxw2-hrv9
  • GO-2026-4534 CVE-2026-25899 GHSA-2mr3-m5q5-wgp6
  • GO-2026-4535 CVE-2026-27585 GHSA-4xrr-hq4w-6vf4
  • GO-2026-4536 CVE-2026-27590 GHSA-5r3v-vc8m-m96g
  • GO-2026-4537 CVE-2026-27589 GHSA-879p-475x-rqh2
  • GO-2026-4538 CVE-2026-27587 GHSA-g7pc-pc7g-h8jh
  • GO-2026-4539 CVE-2026-27586 GHSA-hffm-g8v7-wrv7
  • GO-2026-4540 CVE-2026-25891 GHSA-m3c2-496v-cw3v
  • GO-2026-4541 CVE-2026-27588 GHSA-x76f-jf84-rqj8
  • GO-2026-4543 CVE-2026-25882 GHSA-mrq8-rjmw-wpq3
  • GO-2026-4559 CVE-2026-27141

Update to version 0.0.20260225T230704 2026-02-25T23:07:04Z.

  • GO-2026-4358 CVE-2026-24137 GHSA-fcv2-xgw5-pqxf
  • GO-2026-4361 GHSA-c32p-wcqj-j677
  • GO-2026-4394 CVE-2026-24051 GHSA-9h8m-3fm2-qjrq
  • GO-2026-4399 CVE-2026-25518 GHSA-gx3x-vq4p-mhhv
  • GO-2026-4507 CVE-2026-26314 GHSA-2gjw-fg97-vg3r
  • GO-2026-4508 CVE-2026-26313 GHSA-689v-6xwf-5jf3
  • GO-2026-4509 CVE-2026-27017 GHSA-7m29-f4hw-g2vx
  • GO-2026-4511 CVE-2026-26315 GHSA-m6j8-rg6r-7mv8
  • GO-2026-4512 CVE-2026-26995 GHSA-rrxv-pmq9-x67r
  • GO-2026-4531 CVE-2026-25591 GHSA-w6x6-9fp7-fqm4
  • GO-2026-4532 CVE-2026-25802 GHSA-299v-8pq9-5gjq
  • GO-2026-4533 CVE-2026-27571 GHSA-qrvq-68c2-7grw
  • GO-2026-4542 CVE-2026-27598 GHSA-6v48-fcq6-ff23
  • GO-2026-4545 CVE-2025-50180 GHSA-3c9r-837r-qqm4
  • GO-2026-4546 CVE-2026-27611 GHSA-8vrh-3pm2-v4v6
  • GO-2026-4547 CVE-2026-27626 GHSA-49gm-hh7w-wfvf
  • GO-2026-4548 GHSA-2phg-qgmm-r638

Update to version 0.0.20260223T182315 2026-02-23T18:23:15Z.

  • GO-2026-4392 CVE-2026-24845 GHSA-9m43-p3cx-w8j5
  • GO-2026-4434 CVE-2023-43635 GHSA-4jvr-vj2c-8q37
  • GO-2026-4435 CVE-2023-43636 GHSA-5h7v-g49c-h887
  • GO-2026-4436 CVE-2023-43637 GHSA-g7vp-j25f-h34p
  • GO-2026-4442 GHSA-x9p2-77v6-6vhf
  • GO-2026-4444 CVE-2026-23989 GHSA-9j2f-3rj3-wgpg
  • GO-2026-4445 CVE-2026-25760 GHSA-2286-hxv5-cmp2
  • GO-2026-4446 CVE-2026-24851 GHSA-jq9f-gm9w-rwm9
  • GO-2026-4447 GHSA-vf5j-r2hw-2hrw
  • GO-2026-4448 CVE-2025-64111 GHSA-gg64-xxr9-qhjp
  • GO-2026-4449 CVE-2025-64175 GHSA-p6x6-9mx6-26wj
  • GO-2026-4450 CVE-2026-23632 GHSA-5qhx-gwfj-6jqr
  • GO-2026-4451 CVE-2026-22592 GHSA-cr88-6mqm-4g57
  • GO-2026-4452 CVE-2026-24135 GHSA-jp7c-wj6q-3qf2
  • GO-2026-4453 CVE-2026-23633 GHSA-mrph-w4hh-gx3g
  • GO-2026-4454 GHSA-26gq-grmh-6xm6
  • GO-2026-4455 CVE-2025-70963 GHSA-9f8m-9547-2gqm
  • GO-2026-4456 CVE-2025-13523 GHSA-ffx7-34p2-vm3w
  • GO-2026-4457 CVE-2025-65852 GHSA-rjv5-9px2-fqw6
  • GO-2026-4458 CVE-2026-25793 GHSA-69x3-g4r3-p962
  • GO-2026-4459 CVE-2017-18907 GHSA-42x9-rr3c-gr59
  • GO-2026-4460 CVE-2017-18918 GHSA-5ghq-28r7-qwfj
  • GO-2026-4461 CVE-2026-25804 GHSA-86x4-wp9f-wrr9
  • GO-2026-4462 CVE-2017-18915 GHSA-hxxj-8phw-74vw
  • GO-2026-4463 CVE-2017-18917 GHSA-jxc4-w54c-qv5r
  • GO-2026-4464 CVE-2017-18911 GHSA-m462-mqw4-2c8m
  • GO-2026-4465 GHSA-vhvq-fv9f-wh4q
  • GO-2026-4466 CVE-2026-25791 GHSA-wxrw-gvg8-fqjp
  • GO-2026-4467 CVE-2017-18916 GHSA-x33g-375j-jhf7
  • GO-2026-4471 CVE-2025-66630 GHSA-68rr-p4fp-j59v
  • GO-2026-4473 CVE-2026-25934 GHSA-37cx-329c-33x3
  • GO-2026-4474 CVE-2026-25890 GHSA-4mh3-h929-w968
  • GO-2026-4475 CVE-2026-25889 GHSA-hxw8-4h9j-hq2r
  • GO-2026-4476 CVE-2017-18908…
Record
SUSE-SU-2026:0757-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/slackhq/nebula
Go
 1.7.0 to 1.10.2
1.10.3
github.com/slackhq/nebula
Go
 1.7.0 up to 1.10.3
1.10.3
govulncheck-vulndb
openSUSE:Leap 15.6
 before 0.0.20260226T182644-150000.1.149.1
0.0.20260226T182644-150000.1.149.1
govulncheck-vulndb
openSUSE:Leap 16.0
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-25793 is a high vulnerability (CVSS 7.6) in Slack Nebula, published February 6, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.14%, the 3rd percentile. Fixed in github.com/slackhq/nebula 1.10.3.

References

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